ASoC: Convert wm8991 MICBIAS to a supply widget

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/sound/soc/codecs/wm8991.c b/sound/soc/codecs/wm8991.c
index c9ab3ba..1d46d59 100644
--- a/sound/soc/codecs/wm8991.c
+++ b/sound/soc/codecs/wm8991.c
@@ -770,8 +770,8 @@
 		NULL, 0),
 
 	/* MICBIAS */
-	SND_SOC_DAPM_MICBIAS("MICBIAS", WM8991_POWER_MANAGEMENT_1,
-		WM8991_MICBIAS_ENA_BIT, 0),
+	SND_SOC_DAPM_SUPPLY("MICBIAS", WM8991_POWER_MANAGEMENT_1,
+			    WM8991_MICBIAS_ENA_BIT, 0, NULL, 0),
 
 	SND_SOC_DAPM_OUTPUT("LON"),
 	SND_SOC_DAPM_OUTPUT("LOP"),