HAL: Add new device for voice headset

3-pole headphones not working for voice
usecase due to different backend added
for headset.

add new device for headset to differentiate
from headphones and update mixer path
accordingly.

Change-Id: I29d58e29637534e7d2b6098c5cb89ca6f3b987db
diff --git a/hal/voice.c b/hal/voice.c
index b0b75e5..729ab27 100644
--- a/hal/voice.c
+++ b/hal/voice.c
@@ -73,6 +73,7 @@
         strlcpy(mixer_path, "sidetone-handset", MIXER_PATH_MAX_LENGTH);
         break;
     case SND_DEVICE_OUT_VOICE_HEADPHONES:
+    case SND_DEVICE_OUT_VOICE_HEADSET:
     case SND_DEVICE_OUT_VOICE_ANC_HEADSET:
     case SND_DEVICE_OUT_VOICE_ANC_FB_HEADSET:
         is_sidetone_dev = true;