ASoC: rt5616: add missing mute control for HPVOL

Add missing kcontrol for HPVOL mute control.

Signed-off-by: John Lin <john.lin@realtek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/sound/soc/codecs/rt5616.c b/sound/soc/codecs/rt5616.c
index 3704d07..f527b5b 100644
--- a/sound/soc/codecs/rt5616.c
+++ b/sound/soc/codecs/rt5616.c
@@ -309,6 +309,8 @@
 	/* Headphone Output Volume */
 	SOC_DOUBLE("HP Playback Switch", RT5616_HP_VOL,
 		   RT5616_L_MUTE_SFT, RT5616_R_MUTE_SFT, 1, 1),
+	SOC_DOUBLE("HPVOL Playback Switch", RT5616_HP_VOL,
+		   RT5616_VOL_L_SFT, RT5616_VOL_R_SFT, 1, 1),
 	SOC_DOUBLE_TLV("HP Playback Volume", RT5616_HP_VOL,
 		       RT5616_L_VOL_SFT, RT5616_R_VOL_SFT, 39, 1, out_vol_tlv),
 	/* OUTPUT Control */