hal: Update in_snd_device for USB headphone device use cases

When a USB headphone is inserted and capture is not supported,
select the default in_snd_device to handset mic to fix the
Tx mute issues in voice call usecases.

CRs-Fixed: 2430419, 2430420
Change-Id: I6887135784cb928c1eb53f8fecf6256f6f4eabd4
diff --git a/hal/msm8974/platform.c b/hal/msm8974/platform.c
index adfeaa5..a68f483 100644
--- a/hal/msm8974/platform.c
+++ b/hal/msm8974/platform.c
@@ -5295,6 +5295,8 @@
                 } else {
                     snd_device = SND_DEVICE_IN_VOICE_SPEAKER_MIC;
                 }
+            } else {
+                snd_device = SND_DEVICE_IN_HANDSET_MIC;
             }
         }
     } else if (my_data->use_generic_handset == true &&  //     system prop is enabled