[SeaBIOS] Graphics card pass-through working with two pass pci-initialization

[Gerd Hoffmann]

   Hi,

> At the end of the day I want the pci address space allocation code have
> no hard-coded addresses in there but use the e820 table instead to
> figure how big the address space hole is. Maybe even use multiple holes
> (i.e. also use the memory below mmconfig @ 0xe0000000 with q35).

First cut hacked up & pushed to kraxel.q35

cheers,
   Gerd