ipmi: change device discovery order

The ipmi spec provides an ordering for si discovery.  Change the driver to
match, with the exception of preferring smbios to SPMI as HPs (at least)
contain accurate information in the former but not the latter.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Corey Minyard <cminyard@mvista.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>