audio policy: add binder calls for audio source control

Add binder methods to IAudioPolicyService to control activity
of external audio sources (e.g FM tuner).

Change-Id: I2008308a6a996baeae502b68a790d87281efe2ff
diff --git a/services/audiopolicy/service/AudioPolicyInterfaceImplLegacy.cpp b/services/audiopolicy/service/AudioPolicyInterfaceImplLegacy.cpp
index e4ca5dc..f783437 100644
--- a/services/audiopolicy/service/AudioPolicyInterfaceImplLegacy.cpp
+++ b/services/audiopolicy/service/AudioPolicyInterfaceImplLegacy.cpp
@@ -604,4 +604,16 @@
     return INVALID_OPERATION;
 }
 
+status_t AudioPolicyService::startAudioSource(const struct audio_port_config *source,
+                                  const audio_attributes_t *attributes,
+                                  audio_io_handle_t *handle)
+{
+    return INVALID_OPERATION;
+}
+
+status_t AudioPolicyService::stopAudioSource(audio_io_handle_t handle)
+{
+    return INVALID_OPERATION;
+}
+
 }; // namespace android