ASoC: msm: Add support for 4 channel recording

Enable 4 channel recording in kernel

Signed-off-by: Mingming Yin <mingming@codeaurora.org>
Change-Id: I91c76e21a4080c0542a63555f0258010ed061fc0
diff --git a/sound/soc/msm/qdsp6/q6adm.c b/sound/soc/msm/qdsp6/q6adm.c
index bc5c007..3745b17 100644
--- a/sound/soc/msm/qdsp6/q6adm.c
+++ b/sound/soc/msm/qdsp6/q6adm.c
@@ -489,6 +489,11 @@
 		} else if (channel_mode == 2) {
 			open.dev_channel_mapping[0] = PCM_CHANNEL_FL;
 			open.dev_channel_mapping[1] = PCM_CHANNEL_FR;
+		} else if (channel_mode == 4) {
+			open.dev_channel_mapping[0] = PCM_CHANNEL_FL;
+			open.dev_channel_mapping[1] = PCM_CHANNEL_FR;
+			open.dev_channel_mapping[2] = PCM_CHANNEL_RB;
+			open.dev_channel_mapping[3] = PCM_CHANNEL_LB;
 		} else if (channel_mode == 6) {
 			open.dev_channel_mapping[0] = PCM_CHANNEL_FL;
 			open.dev_channel_mapping[1] = PCM_CHANNEL_FR;