PM / runtime: Fetch runtime PM callbacks using a macro

PM / runtime: Fetch runtime PM callbacks using a macro

While fetching the proper runtime PM callback, we walk the hierarchy of
device's power domains, subsystems and drivers.

This is common for rpm_suspend(), rpm_idle() and rpm_resume(). Let's
clean up the code by using a macro that handles this.

Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
(cherry picked from commit 5f59df79837bb809f3945613aba5519cd9755a53)
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>