PM: sleep: core: Rework the power.may_skip_resume handling

Because the power.may_skip_resume device status bit is taken
into account in combination with the DPM_FLAG_LEAVE_SUSPENDED
driver flag, it can be set to 'true' for all devices in the
"suspend" phase of a suspend-resume cycle, so do that.

Then, neither the PM core nor the middle-layer (sybsystem) code
handling it needs to set it to 'true' any more and it just has
to be cleared if there is a reason to avoid skipping the "noirq"
and "early" resume callbacks provided by the driver, so update
the code in question accordingly.

Suggested-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>