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/include/media/IAudioPolicyService.h b/include/media/IAudioPolicyService.h
index 7506153..413267b 100644
--- a/include/media/IAudioPolicyService.h
+++ b/include/media/IAudioPolicyService.h
@@ -155,6 +155,11 @@
     virtual audio_mode_t getPhoneState() = 0;
 
     virtual status_t registerPolicyMixes(Vector<AudioMix> mixes, bool registration) = 0;
+
+    virtual status_t startAudioSource(const struct audio_port_config *source,
+                                      const audio_attributes_t *attributes,
+                                      audio_io_handle_t *handle) = 0;
+    virtual status_t stopAudioSource(audio_io_handle_t handle) = 0;
 };