ASoC: wm5100: Mark register cache as dirty when regulators are disabled

Otherwise we won't resync later.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/sound/soc/codecs/wm5100.c b/sound/soc/codecs/wm5100.c
index fb757af..89f2af7 100644
--- a/sound/soc/codecs/wm5100.c
+++ b/sound/soc/codecs/wm5100.c
@@ -1405,6 +1405,7 @@
 
 	case SND_SOC_BIAS_OFF:
 		regcache_cache_only(wm5100->regmap, true);
+		regcache_mark_dirty(wm5100->regmap);
 		if (wm5100->pdata.ldo_ena)
 			gpio_set_value_cansleep(wm5100->pdata.ldo_ena, 0);
 		regulator_bulk_disable(ARRAY_SIZE(wm5100->core_supplies),