r294672 in 10-stable breaks Xserve G5

[Bill Sorenson]

I had an issue with my G5 booting 10.3. Eventually to narrow the issue
down I undid the MFC r289704 to 10-stable, specifically the change to
sys/dev/ofw/ofw_iicbus.c and now my kernel boots.

I'm working on figuring out where the real breakage is. It seems some
where the powermac code is hacking around that bug that was fixed. If
anybody knows this stuff better than me let me know.

Thanks,
Bill S.