[LinuxBIOS] A8N5X port

[Robert Millan]

This patch includes config files for the asus/a8n5x port.  It is the same as
asus/a8n_e with a different pnp layout, so I used #include's whenever possible.

System boots and is usable with usb keyboard.

works:

- serial port
  - vga (old pci card)
  - memtest86+ succeeds, but only with Rudolf's patch for unbuffered dimms
    in K8.  Otherwise you get spurious memory corruption.
  - ide disk
  - usb

doesn't:

- ps/2 keyboard
  - onboard ethernet
  - vga pci-e card (??)
  - any other pci card I tried

wasn't tested:

- sata
  - game port
  - onboard audio (not supported by alsa anyway)
  - ps/2 mouse