Add support for DEC/Intel 21150 PCI-PCI bridge

[Peter Dufault]

I want to add support for the DEC/Intel 21150 PCI-PCI bridge, initially 
for the MVME5500 so I can use a Motorola PMCSPAN to get more PMC slots.

I see the code in mvme5500/pci/pci.c where it detects bridges, and I 
did the trivial change to have it find the DEC 21150, but I don't see 
where bridges are setup.  I looked at the 21150 documentation, and it 
seems as if it won't be too much work to get it set up and after that 
things should "just work".

I don't know much about this yet, and any pointers on what to change 
and how things are going to go in the future (for more generic PCI 
support instead of in the mvme5500 tree!) will help.

Thanks,

Peter

Peter Dufault
HD Associates, Inc.