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/AudioPolicyService.h b/services/audiopolicy/service/AudioPolicyService.h
index fbd8f0e..4e25d33 100644
--- a/services/audiopolicy/service/AudioPolicyService.h
+++ b/services/audiopolicy/service/AudioPolicyService.h
@@ -192,6 +192,11 @@
 
     virtual status_t registerPolicyMixes(Vector<AudioMix> mixes, bool registration);
 
+    virtual status_t startAudioSource(const struct audio_port_config *source,
+                                      const audio_attributes_t *attributes,
+                                      audio_io_handle_t *handle);
+    virtual status_t stopAudioSource(audio_io_handle_t handle);
+
             status_t doStopOutput(audio_io_handle_t output,
                                   audio_stream_type_t stream,
                                   audio_session_t session);