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/AudioDumpInterface.h b/libs/audioflinger/AudioDumpInterface.h
index 1136ce1..5b9a6b1 100644
--- a/libs/audioflinger/AudioDumpInterface.h
+++ b/libs/audioflinger/AudioDumpInterface.h
@@ -56,8 +56,9 @@
     void                Close(void);
     AudioStreamOut*     finalStream() { return mFinalStream; }
     uint32_t            device() { return mDevice; }
-
     int                 getId()  { return mId; }
+    virtual status_t    getRenderPosition(uint32_t *dspFrames);
+
 private:
     AudioDumpInterface *mInterface;
     int                  mId;