ALSA: wm8750: add missing VREF output

Add missing output VREF. After a65f0568f6cc8433877fb71dd7d36b551854b0bc
it's critical, since it makes chip routing initialisation to fail.

Signed-off-by: Dmitry Baryshkov <dbaryshkov@gmail.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/soc/codecs/wm8750.c b/sound/soc/codecs/wm8750.c
index 2e71394..c6a8edf 100644
--- a/sound/soc/codecs/wm8750.c
+++ b/sound/soc/codecs/wm8750.c
@@ -350,6 +350,7 @@
 	SND_SOC_DAPM_OUTPUT("ROUT2"),
 	SND_SOC_DAPM_OUTPUT("MONO1"),
 	SND_SOC_DAPM_OUTPUT("OUT3"),
+	SND_SOC_DAPM_OUTPUT("VREF"),
 
 	SND_SOC_DAPM_INPUT("LINPUT1"),
 	SND_SOC_DAPM_INPUT("LINPUT2"),