ASoC: rt5645: Use update_bits for bit control

In codec bias level off, we need to disable gate mode with MCLK
for power saving. It is set by one bit. We don't need to write
while register for that.
Signed-off-by: NBard Liao <bardliao@realtek.com>
Signed-off-by: NMark Brown <broonie@kernel.org>

sound/soc/codecs/rt5645.c

@@ -2396,7 +2396,8 @@ static int rt5645_set_bias_level(struct snd_soc_codec *codec,
 
 	case SND_SOC_BIAS_OFF:
 		snd_soc_write(codec, RT5645_DEPOP_M2, 0x1100);
-		snd_soc_write(codec, RT5645_GEN_CTRL1, 0x0128);
+		snd_soc_update_bits(codec, RT5645_GEN_CTRL1,
+				RT5645_DIG_GATE_CTRL, 0);
 		snd_soc_update_bits(codec, RT5645_PWR_ANLG1,
 				RT5645_PWR_VREF1 | RT5645_PWR_MB |
 				RT5645_PWR_BG | RT5645_PWR_VREF2 |