hal: add support for LINE IN device

Vipertooth has hardware support for LINE IN device.
Adding support in audio hal to select line-in device.

Change-Id: Ia783ef986724a51a25a33f91df05b58984ecc87d
diff --git a/hal/msm8916/platform.h b/hal/msm8916/platform.h
index 2a71f9e..8bb0a3c 100644
--- a/hal/msm8916/platform.h
+++ b/hal/msm8916/platform.h
@@ -234,6 +234,7 @@
     SND_DEVICE_IN_INCALL_REC_RX,
     SND_DEVICE_IN_INCALL_REC_TX,
     SND_DEVICE_IN_INCALL_REC_RX_TX,
+    SND_DEVICE_IN_LINE,
     SND_DEVICE_IN_END,
 
     SND_DEVICE_MAX = SND_DEVICE_IN_END,