Return a low priority for the "hostb%d" catch-all for pci busses, which will

Return a low priority for the "hostb%d" catch-all for pci busses, which will
allow compiled-in bus device drivers such as AGP to attach first.  Without
this the probe order is half hazzard and in particular SMP boxes may attach
"hostb" first, preventing AGP from attaching.

Note that AGP will still not load properly from loader.conf or after booting
with kldload.  Removing the "hostb" catch-all entirely solves that problem
but some additional investigation must be done first.

AGP-problems-reported-by: Adam K Kirchhoff <adamk@voicenet.com>