PM: runtime: Allow to call __pm_runtime_set_status() from atomic context

The only two users of __pm_runtime_set_status() are pm_runtime_set_active()
and pm_runtime_set_suspended(). These are widely used and should be called
from non-atomic context to work as expected. However, it would be
convenient to allow them be called from atomic context too, as shown from a
subsequent change, so let's add support for this.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Maulik Shah <quic_mkshah@quicinc.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>