ASoC: wm8990: Mark the register map as dirty when powering down

Otherwise we'll skip sync on resume.

Signed-off-by: Mark Brown <broonie@linaro.org>
Acked-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Cc: stable@vger.kernel.org

sound/soc/codecs/wm8990.c

@@ -1259,6 +1259,8 @@ static int wm8990_set_bias_level(struct snd_soc_codec *codec,
 
 		/* disable POBCTRL, SOFT_ST and BUFDCOPEN */
 		snd_soc_write(codec, WM8990_ANTIPOP2, 0x0);
+
+		codec->cache_sync = 1;
 		break;
 	}