- scan for VGABIOS ROM after rombios32 init
- copy PCI ROM to shadow RAM at 0xc0000 and enable it
- NOTE: this feature does not work with BIOS-bochs-legacy, so we should recommend to use the
default BIOS for PCI display adapters
- TODO: load VGABIOS ROM from the vga code instead of main.cc if PCI is disabled