DDB-5074 patch

[p2@mind.be (Peter De Schrijver)]

Hi,

Attached you will find a patch against the latest CVS kernel from oss.sgi.com
to fix the support for the NEC DDB-5074 evaluation board. Onboard
ethernet works now, as well as ps/2 keyboard support. PS/2 mouse support
might work as well. I didn't try it yet. Matrox Millenium II framebuffer
also works now. I didn't try other graphics boards, but it seems most of
them need some magic to work which only the (IA32-only) firmware knows
of.

Changes since last version :

+ Changes ddb_sync into NOP. This at last makes the system stable under
  high IRQ load. 
+ Some tweaks to the IRQ handler
+ Changed PCI BAR0 to 0, so main memory resides at address 0 in PCI
  address space.

TODO :

Add support for the NILE 4 watchdog timer
Add MTD support
Test other PCI cards (eg. SCSI or IDE cards)
Find a way to use the NILE 4 UART

Have Fun,

Peter.