ALSA: wm8750: add missing VREF output

Add missing output VREF. After a65f0568f6
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>

sound/soc/codecs/wm8750.c

@@ -350,6 +350,7 @@ static const struct snd_soc_dapm_widget wm8750_dapm_widgets[] = {
 	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"),