I just tried booting coreboot with vgabios.bin as per http://www.coreboot.org/ASUS_F2A85-M but *without* the seabios patch there.
The system boots ok, the on-CPU graphics are initialized, and everything seems to be working. I am using seabios head (ed88f6515c18d9520efa4a41ccb70038dfbe43f9) and coreboot head (4c2ebeba78e437df2d156a4c68f1fb15b62926f5).
I could attempt a bisection search to find when the patch was last needed. However, can you or Sage Engineering confirm this? I can update the wiki entry for the board if the patch is not needed any more.