ASoC: soc-pcm: Drop the redundant snd_soc_dai_digital_mute() in soc_pcm_close()

This patch removed the redundant snd_soc_dai_digital_mute() in close() since
it's better to mute in hw_free() which's slightly earlier and symmetrical for
the case of reconfiguration: 'aplay 44k1.wav 48k.wav', for example, will be
open()->hw_params()->prepare(unmute)->playi1ng->hw_free(mute)->hw_params()->
parepare(unmute)->playing->hw_free(mute)->close()

Signed-off-by: Nicolin Chen <b42378@freescale.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/soc-pcm.c

@@ -390,11 +390,6 @@ static int soc_pcm_close(struct snd_pcm_substream *substream)
 	if (!codec_dai->active)
 		codec_dai->rate = 0;
 
-	/* Muting the DAC suppresses artifacts caused during digital
-	 * shutdown, for example from stopping clocks.
-	 */
-	snd_soc_dai_digital_mute(codec_dai, 1, substream->stream);
-
 	if (cpu_dai->driver->ops->shutdown)
 		cpu_dai->driver->ops->shutdown(substream, cpu_dai);