mptable: Don't describe pci-to-pci bridges.

It should not be necessary to describe PCI-to-PCI bridges in the
mptable.  (The mptable was designed to fit in ROM, so it seems
unlikely that it would be used for bridges that could be dynamically
added.)  Describing only the root bus should make it easier to port
this content into QEMU.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
mptable: Use same PCI irqs as ACPI code.

The ACPI code has a hardcoded list of PCI interrupts.  Use that same
list in the mptable code generation.  This will ensure that both
tables are in synch - it may also make the mptable easier to generate
from QEMU.

Also, move the irq0_override lookup outside of the irq loop.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>
pciinit: Enable default VGA device

As QEMU gains PCI bridge and PCIe root port support, we won't always
find the VGA device on the root bus.  We therefore need to add support
to find and enable a VGA device and the path to it through the VGA
Enable support in the PCI bridge control register.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
acpi: make default DSDT optional

Since commit f7e4dd6c18ccfbaf6cd2f5eaaed2b77cabc8a406 QEMU loads its
own copy of DSDT, so let's not build in PIIX.  This makes building in
the DSDT an option, default to on (built-in).  If no one complains for a
while, we'll be able to switch it off and then maybe remove altogether.

With CONFIG_ACPI_DSDT = y
Total size: 127348  Fixed: 58892  Free: 3724 (used 97.2% of 128KiB rom)
With CONFIG_ACPI_DSDT = n
Total size: 122844  Fixed: 58884  Free: 8228 (used 93.7% of 128KiB rom)

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>