ASoC: pcm: 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>

sound/soc/soc-pcm.c

@@ -417,8 +417,9 @@ static int soc_pcm_close(struct snd_pcm_substream *substream)
 		} else {
 			/* start delayed pop wq here for playback streams */
 			rtd->pop_wait = 1;
-			schedule_delayed_work(&rtd->delayed_work,
-				msecs_to_jiffies(rtd->pmdown_time));
+			queue_delayed_work(system_power_efficient_wq,
+					   &rtd->delayed_work,
+					   msecs_to_jiffies(rtd->pmdown_time));
 		}
 	}