hal: add support for device mute

Add support for muting the RX and TX devices without affecting
the voice stream. This feature is added to enable voice call
quality testing by carriers.

CRs-Fixed: 634690
Change-Id: I4d0f599e44ae24ce02d29333f496ef18f889ac55
diff --git a/hal/msm8960/platform.c b/hal/msm8960/platform.c
index 298c60d..dacf68e 100644
--- a/hal/msm8960/platform.c
+++ b/hal/msm8960/platform.c
@@ -551,6 +551,12 @@
     return ret;
 }
 
+int platform_set_device_mute(void *platform, bool state, char *dir)
+{
+    LOGE("%s: Not implemented", __func__);
+    return -ENOSYS;
+}
+
 snd_device_t platform_get_output_snd_device(void *platform, audio_devices_t devices)
 {
     struct platform_data *my_data = (struct platform_data *)platform;