power: move pm_qos update timeout handler to power-efficient workqueue

To avoid waking up idle CPUs, allow the scheduler to select the best CPU
to handle pm_qos update timeouts. This extends idle residency times and
conserves power.

This functionality is enabled when CONFIG_WQ_POWER_EFFICIENT is selected.

Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <len.brown@intel.com>
Signed-off-by: Shaibal Dutta <shaibal.dutta@broadcom.com>
[zoran.markovic@linaro.org: Rebased to latest kernel. Fixed code alignment.
Added commit message.]
Signed-off-by: Zoran Markovic <zoran.markovic@linaro.org>
Signed-off-by: mydongistiny <jaysonedson@gmail.com>