Fix issue 2285561: New AudioFlinger and audio driver API needed for A/V sync

Added getRenderPosition() API to IAudioFlinger to retreive number of audio frames
written by AudioFlinger to audio HAL and by DSP to DAC.

Added getRenderPosition() API to AudioHardwareInterface to retreive number of audio frames
written by DSP to DAC.

Exposed AudioTrack::getPosition() to AudioSink() to make it available to media player.

Removed excessive log in AudioHardwareGeneric.
diff --git a/libs/audioflinger/AudioHardwareGeneric.h b/libs/audioflinger/AudioHardwareGeneric.h
index 42da413..95c7ea3 100644
--- a/libs/audioflinger/AudioHardwareGeneric.h
+++ b/libs/audioflinger/AudioHardwareGeneric.h
@@ -55,6 +55,7 @@
     virtual status_t    dump(int fd, const Vector<String16>& args);
     virtual status_t    setParameters(const String8& keyValuePairs);
     virtual String8     getParameters(const String8& keys);
+    virtual status_t    getRenderPosition(uint32_t *dspFrames);
 
 private:
     AudioHardwareGeneric *mAudioHardware;