ASoC: Leave input audio data bit length settings untouched in wm8711_set_dai_fmt

Current implementation in wm8711_set_dai_fmt always clear BIT[3:2]
(the Input Audio Data Bit Length Select) of WM8711_IFACE(07h) register.
Input Audio Data Bit Length Select bits are set by wm8711_hw_params,
we should leave BIT[3:2] untouched in wm8711_set_dai_fmt.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: stable@kernel.org

sound/soc/codecs/wm8711.c

@@ -232,7 +232,7 @@ static int wm8711_set_dai_fmt(struct snd_soc_dai *codec_dai,
 		unsigned int fmt)
 {
 	struct snd_soc_codec *codec = codec_dai->codec;
-	u16 iface = 0;
+	u16 iface = snd_soc_read(codec, WM8711_IFACE) & 0x000c;
 
 	/* set master/slave audio interface */
 	switch (fmt & SND_SOC_DAIFMT_MASTER_MASK) {