PCI: Turn pci_fixup_video into generic for embedded VGA
pci_fixup_video turns into generic code because there are many platforms need this fixup
for embedded VGA as well as x86. The Video BIOS integrates into System BIOS on a machine
has embedded VGA although embedded VGA generally don't have PCI ROM. As a result,
embedded VGA need the way that the sysfs rom points to the Video BIOS of System
RAM (0xC0000). PCI-to-PCI Bridge Architecture specification describes the condition whether
or not PCI ROM forwards VGA compatible memory address. fixup_video suits this specification.
Although the Video ROM generally implements in x86 code regardless of platform, some
application such as X Window System can run this code by dosemu86. Therefore,
pci_fixup_video should turn into generic code.