ASoC: rt5640: Power down LDO while suspended

If we have control over the LDO then disable it during suspend; the device
is already being put into reset so will be non-functional over suspend
anyway and this will save a small amount of power.
Signed-off-by: Mark Brown <broonie@linaro.org>
Tested-by: Stephen Warren <swarren@nvidia.com>

sound/soc/codecs/rt5640.c

@@ -1979,12 +1979,20 @@ static int rt5640_suspend(struct snd_soc_codec *codec)
 	rt5640_reset(codec);
 	regcache_cache_only(rt5640->regmap, true);
 	regcache_mark_dirty(rt5640->regmap);
+	if (gpio_is_valid(rt5640->pdata.ldo1_en))
+		gpio_set_value_cansleep(rt5640->pdata.ldo1_en, 0);
 
 	return 0;
 }
 
 static int rt5640_resume(struct snd_soc_codec *codec)
 {
+	struct rt5640_priv *rt5640 = snd_soc_codec_get_drvdata(codec);
+
+	if (gpio_is_valid(rt5640->pdata.ldo1_en)) {
+		gpio_set_value_cansleep(rt5640->pdata.ldo1_en, 1);
+		msleep(400);
+	}
 	rt5640_set_bias_level(codec, SND_SOC_BIAS_STANDBY);
 
 	return 0;