regulator: core: Use the power efficient workqueue for delayed powerdown

There is no need to use a normal per-CPU workqueue for delayed power downs
as they're not timing or performance critical and waking up a core for them
would defeat some of the point.
Signed-off-by: Mark Brown <broonie@linaro.org>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Liam Girdwood <liam.r.girdwood@intel.com>

drivers/regulator/core.c

@@ -1890,8 +1890,9 @@ int regulator_disable_deferred(struct regulator *regulator, int ms)
 	rdev->deferred_disables++;
 	mutex_unlock(&rdev->mutex);
 
-	ret = schedule_delayed_work(&rdev->disable_work,
-				    msecs_to_jiffies(ms));
+	ret = queue_delayed_work(system_power_efficient_wq,
+				 &rdev->disable_work,
+				 msecs_to_jiffies(ms));
 	if (ret < 0)
 		return ret;
 	else