Another ppbus/ppc cleanup patch...

[John Baldwin]

This is another round of cleanups to the ppbus/ppc drivers.  Mostly this 
removes the use of unit numbers instead using device_printf() and if_printf() 
for messages and using if_softc and si_drv1 and device_t members in softc 
structures instead of looking up device_t and softc structures using unit 
numbers.

http://www.FreeBSD.org/~jhb/patches/ppc_cleanup.patch

-- 
John Baldwin