If we are resuming non-MPSAFE drivers, they need Giant held for them.
This may fix some obscure suspend/resume problems. It has fixed keyrate
setting problems that were triggered by cardbus (MPSAFE) changing the
ordering for syscons resume (non-MPSAFE). Also, add some asserts that
Giant is held in our suspend/resume and shutdown methods.
Found by: iedowse
MFC after: 2 days