pseries: SLOF PCI flag day

Currently on the pseries machine the SLOF firmware is used normally,
but we bypass it when -kernel is specified.  Having these two

different boot paths can cause some confusion.

In particular at present we need to "probe" the (emulated) PCI bus and
produce device tree nodes for the PCI devices in qemu, for the -kernel
case.  In the SLOF case, it takes the device tree from qemu adds some
stuff to it then passes it on to the kernel.

It's been decided that a better approach is to always boot through
SLOF, even when using -kernel.  WIth this approach we can leave PCI
probing and device node creation to SLOF in all cases which removes a
bunch of code in qemu, and avoids iterating the PCI devices from the
machine specific init code which we're not supposed to do.

This patch changes qemu to always boot through SLOF, and not to create
PCI nodes.  Simultaneously it updates the included version of SLOF
(submodule and binary image) to one which supports (and requires) the
new approach.

The new SLOF version also includes a number of unrelated enhancements:
support for booting from virtio-pci devices and e1000, greatly
improved FCode support and many bugfixes.  It also makes SLOF ready to
be used even when specifying a kernel on the qemu command line.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>
