qemu vfio-pci: Graphics device quirks

Graphics cards have a number of different backdoors.  Some of these
are alternative ways to get PCI BAR addresses, some of them are
complete mirrors of PCI config space available through MMIO and
I/O port access.  These quirks cover a number of ATI Radeon and
Nvidia devices.  On the ATI/AMD side, this should enable HD5450
and HD7850 and hopefully a host of devices around those generations.
For Nvidia, my card selection is much more dated.  A 8400gs works
well with both the Window shipped driver and the Nvidia downloaded
driver.  A 7300le works as well, with the caveat that generating
the Window experience index with the Nvidia driver causes the card
to reset several times before generating a BSOD.  An NVS 290 card
seems to run well with the shipped Windows driver, but generates
a BSOD with the Nvidia driver.  All of the Nvidia devices work with
the Linux Nvidia proprietary driver and nouveau, the HD5450 works
with either radeon or fglrx, HD7850 works with vesa and fglrx (not
supported by radeon).  Extremely limited 3D testing.

Device reset is also an issue with graphics.  It's unfortunately
very common that the devices offer no means to reset the card or
doesn't seem effective.  Nvidia devices are pretty good about being
able to get the device to a working state through the VGA BIOS init,
Radeon devices less so, and often require a host reboot.  Work
remains to be done here.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
