roms: update seabios submodule to 31b8b4eea9d9ad58a73b22a6060d3ac1c419c26d

Updates seabios to git master snapshot.  seabios is in freeze now,
update to final 1.7.4 will follow later this year.

Summary of major changes:

 * Support for acpi table loading from qemu.
 * Support for the xhci host adapter.
 * Support for the pvscsi HBA.
 * Various minor bug fixes.
 * Lots of cleanups.

Full shortlog since 1.7.3 (note that some of these changes have been
cherry-picked into 1.7.3-stable):

Evgeny Budilovsky (1):
      Add pvscsi boot support

Gerd Hoffmann (27):
      coreboot: add cbmem console support
      Add CONFIG_DEBUG_COREBOOT config option
      apm: fix shutdown
      ahci: add missing check for allocation failure
      bochsvga: fallback to stdvga if dispi interface isn't present
      Add generic qemu detection
      Drop coreboot qemu detection
      Add qemu detection to csm
      uas: add (temporary) superspeed stopgap
      usb: add usb_update_pipe()
      usb: add xhci support
      fix buildversion.sh
      build: simplify cross builds
      build: create output dirs in do-kconfig
      build: explicitly set ROM size
      Add qemu_cfg_e820 function.
      Add support for etc/e820 fw_cfg file
      pci: don't reorder entries when moving to 64bit list
      pci: don't map usb host adapters above 4G
      pci: align 64bit pci regions to 1G
      pci: tweak + comment minimum allocations
      pci: log pci windows
      pci: map 64-bit BARs at location provided by emulator
      ahci: zap real mode macros
      ahci: remote some parentheses
      ahci: alloc structs in high memory
      add hw/serialio.c to SRC32SEG

Jonathan A. Kollasch (1):
      vgahooks: add SM720 VGA BIOS hooks for WIN Enterprises MB-60470

Kevin O'Connor (80):
      Fix USB EHCI detection that was broken in hlist conversion of PCIDevices.
      Update README to include info on VARLOW variables.
      PIC code cleanups.
      Move internal timer code from clock.c to a new file timer.c.
      Don't pass khz to pmtimer_setup - it's always PM_TIMER_FREQUENCY.
      Add helper functions to convert timer irqs to milliseconds.
      Improve accuracy of internal timers.
      Rename cpu_khz to TimerKHz.
      Shift CPU TSC down to reduce need for 64bit variables.
      Rename check_timer() function (and similar) to irqtimer_check().
      Rename check_tsc() (and similar) to timer_check() and use u32.
      Separate out timer setup code.
      Unify pmtimer_read() and pittimer_read() code.
      Default unused UMB areas to be read-only.
      Add missing mathcp_setup() call to CSM code.
      Fix bug in CBFS file walking with compressed files.
      Support custom boot menu prompt and custom boot menu key.
      Minor cleanups to smm assembler.
      Add config option to support memory allocations in 9-segment.
      Minor - no need to declare MaxCountCPUs as VARFSEG.
      Minor - simplify rom_reserve().
      Rename tools/ directory to scripts/ directory.
      Update kconfig to latest version.
      build: Don't use vpath makefile directive.
      Move code centered around specific hardware devices to src/hw/
      Move code cenetered around firmware initialization to src/fw/
      build: Reorder makefile source list to group like files together.
      README: Update readme to note scripts/ directory rename and vgasrc/ directory.
      vgabios: Rename stdvga_bpp_factor to stdvga_vram_ratio.
      vgabios: Limit the range of the VBE number of "pages" parameter.
      readme: Minor - fix typo in readme.
      Split x86 specific functions out of util.c/h to new files x86.c/h.
      Move keyboard calling code from util.c to boot.c.
      Rename util.c to string.c and introduce string.h.
      build: Perform compile checking on vgasrc code.
      Move stacks.c definitions from util.h to new file stacks.h.
      Move romfile definitions from util.h to new file romfile.h.
      Move malloc code from pmm.c to new files malloc.c and malloc.h.
      Move function definitions for output.c from util.h to new file output.h.
      Move definition of struct segoff_s from farptr.h to types.h.
      build: Fix import of gcc dependency files.
      Move pirtable definitions from hw/pci.h to std/pirtable.h and util.h.
      Move optionroms.h to std/optionrom.h and util.h.
      Move vbe.h to std/vbe.h.
      Move fw/LegacyBios.h to std/LegacyBios.h and remove csm.h.
      Move fw/smbios.h to std/smbios.h.
      Move fw/mptable.h to std/mptable.h.
      Move fw/acpi.h to std/acpi.h.
      Move pnpbios definition to new file std/pnpbios.h.
      Move pmm definitions to new file std/pmm.h.
      Split disk.h into block.h and std/disk.h.
      Move standard bda type info from biosvar.h to std/bda.h.
      Merge bmp.h, boot.h, jpeg.h, and post.h into util.h.
      Sort the sections of util.h.
      Move PIT setup from clock.c to hw/timer.c.
      Rename hw/cmos.h to hw/rtc.h and copy RTC code from clock.c to hw/rtc.c.
      Move dma code to new file hw/dma.c.
      Remove ioport.h; disperse its contents to other header files.
      Minor - update file comments in src/malloc.c.
      Rename fields of 'struct chs_s' and use in floppy lba2chs().
      Rearrange stack_hop_back() call in wait_irq, check_irqs, and _farcall16.
      Minor - move call16 assembler in romlayout.S.
      Make __call16 use C calling convention and support two passed parameters.
      Update _farcall16() to pass segment of callregs explicitly.
      Support call16() calls after entering 32bit mode from call32().
      Run ahci code entirely in 32bit mode.
      Build different final files for QEMU, coreboot, and CSM.
      Convert op->drive_g from a 16bit pointer to a 32 bit "GLOBALFLAT" pointer.
      megasas: Don't attempt to access 'struct pci_device' at runtime.
      Minor - eliminate the SET_GLOBAL macro.
      Move low-level hardware writing from output.c to new file hw/serialio.c.
      vgabios: Load the DAC palette in "packed" modes on Cirrus and BochsVGA.
      vgabios: Support custom fonts in vga framebuffer text writing.
      vgabios: Add bochsvga "HDTV" resolutions.
      vgabios: Avoid possible divide by zero in bochsvga_set_displaystart.
      vgabios: Work around lack of support for "calll" in x86emu emulation.
      Minor - update file comment on bootsplash.c.
      vgabios: Support allocating an extra stack for vgabios calls and default on.
      vgabios: Move initialization code to new file vgainit.c.
      floppy: Minor - add warnings if timeouts occur.

Michael S. Tsirkin (6):
      acpi: sync FADT flags from PIIX4 to Q35
      acpi_extract.py: document DEVICE directives
      biostables: support looking up RSDP
      romfile_loader: utility to patch in-memory ROM files
      acpi: load and link tables through romfile loader
      acpi: strip compiler info in built-in DSDT if any

Paul Menzel (2):
      ACPI DSDT: Make control method `IQCR` serialized
      hw/usb-xhci.c: Code refactoring to not override initializers in `speed_from_xhci[16]`

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
