Add Quad channel output to AudioPolicyManager

Matches some USB device configurations.

Change-Id: I2429f9de87816b4ad1d39516e3821562617c76ee
diff --git a/services/audiopolicy/AudioPolicyManager.cpp b/services/audiopolicy/AudioPolicyManager.cpp
index c5248fe..603c44b 100644
--- a/services/audiopolicy/AudioPolicyManager.cpp
+++ b/services/audiopolicy/AudioPolicyManager.cpp
@@ -147,6 +147,7 @@
 const StringToEnum sOutChannelsNameToEnumTable[] = {
     STRING_TO_ENUM(AUDIO_CHANNEL_OUT_MONO),
     STRING_TO_ENUM(AUDIO_CHANNEL_OUT_STEREO),
+    STRING_TO_ENUM(AUDIO_CHANNEL_OUT_QUAD),
     STRING_TO_ENUM(AUDIO_CHANNEL_OUT_5POINT1),
     STRING_TO_ENUM(AUDIO_CHANNEL_OUT_7POINT1),
 };