ASoC: wm8731: Convert to snd_soc_cache_sync

Convert to snd_soc_cache_sync for sync reg_cache with the hardware.
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/codecs/wm8731.c

@@ -427,9 +427,7 @@ static int wm8731_set_bias_level(struct snd_soc_codec *codec,
 				 enum snd_soc_bias_level level)
 {
 	struct wm8731_priv *wm8731 = snd_soc_codec_get_drvdata(codec);
-	int i, ret;
-	u8 data[2];
-	u16 *cache = codec->reg_cache;
+	int ret;
 	u16 reg;
 
 	switch (level) {
@@ -444,16 +442,7 @@ static int wm8731_set_bias_level(struct snd_soc_codec *codec,
 			if (ret != 0)
 				return ret;
 
-			/* Sync reg_cache with the hardware */
-			for (i = 0; i < ARRAY_SIZE(wm8731_reg); i++) {
-				if (cache[i] == wm8731_reg[i])
-					continue;
-
-				data[0] = (i << 1) | ((cache[i] >> 8)
-						      & 0x0001);
-				data[1] = cache[i] & 0x00ff;
-				codec->hw_write(codec->control_data, data, 2);
-			}
+			snd_soc_cache_sync(codec);
 		}
 
 		/* Clear PWROFF, gate CLKOUT, everything else as-is */