late suspend/early resume

[Justin Hibbits]

I'd like to solicit opinions on adding new kobj device API calls,
device_late_suspend and device_early_resume.

I've been working on PowerPC suspend/resume, and certain devices must be
suspended last and resumed first on Apple hardware, namely the chipsets.
It happens that one device (uninorth) appears first in the devinfo chain,
while the other (mac-io) appears off a later PCI bus.  So, rather than
special casing this to suspend the mac-io and its children, as well as the
uninorth, last with specific calls, I'd like to add a device_suspend_late
and device_resume_early, that would simply be identical to
device_suspend/device_resume, but could be called after and before,
respectively, to do last minute order suspend and first pass
initialization, to initialize things like clocks required for other devices.

It's not difficult to explicitly call suspend and resume functions on the
chipsets, but I think it's cleaner to do it through the newbus/kobj
interface, and it might be useful for other architectures as well.

Thoughts?

- Justin