PM / Runtime: Clear power.deferred_resume on success in rpm_suspend()

The power.deferred_resume can only be set if the runtime PM status
of device is RPM_SUSPENDING and it should be cleared after its
status has been changed, regardless of whether or not the runtime
suspend has been successful.  However, it only is cleared on
suspend failure, while it may remain set on successful suspend and
is happily leaked to rpm_resume() executed in that case.

That shouldn't happen, so if power.deferred_resume is set in
rpm_suspend() after the status has been changed to RPM_SUSPENDED,
clear it before calling rpm_resume().  Then, it doesn't need to be
cleared before changing the status to RPM_SUSPENDING any more,
because it's always cleared after the status has been changed to
either RPM_SUSPENDED (on success) or RPM_ACTIVE (on failure).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable@vger.kernel.org