hal: update QCHAT pcm device ID for external codec hardware

Update QCHAT pcm device ID as per the machine driver. This is to
support QCHAT on msm8939 external codec hardware.
Also, modify the logic to select different pcm device ID's for
an usecase based on codec type.

CRs-Fixed: 820740
Change-Id: I6bfd99655a9f8a0953796ba8910ddec891e3821a
diff --git a/hal/msm8916/platform.h b/hal/msm8916/platform.h
index 7e87a3c..5375f60 100644
--- a/hal/msm8916/platform.h
+++ b/hal/msm8916/platform.h
@@ -244,6 +244,7 @@
 #define VOICE2_CALL_PCM_DEVICE 13
 #define VOLTE_CALL_PCM_DEVICE 15
 #define QCHAT_CALL_PCM_DEVICE 26
+#define QCHAT_CALL_PCM_DEVICE_OF_EXT_CODEC 28
 #define VOWLAN_CALL_PCM_DEVICE 16
 
 #define AFE_PROXY_PLAYBACK_PCM_DEVICE 7