thermal: core: Suspend thermal zones later and resume them earlier

thermal: core: Suspend thermal zones later and resume them earlier

To avoid some undesirable interactions between thermal zone suspend
and resume with user space that is running when those operations are
carried out, move them closer to the suspend and resume of devices,
respectively, by updating dpm_prepare() to carry out thermal zone
suspend and dpm_complete() to start thermal zone resume (that will
continue asynchronously).

This also makes the code easier to follow by removing one, arguably
redundant, level of indirection represented by the thermal PM notifier.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Armin Wolf <W_Armin@gmx.de>
Link: https://patch.msgid.link/2036875.PYKUYFuaPT@rafael.j.wysocki