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/AudioFlinger.h b/libs/audioflinger/AudioFlinger.h
index 52999b1..44da9ed 100644
--- a/libs/audioflinger/AudioFlinger.h
+++ b/libs/audioflinger/AudioFlinger.h
@@ -136,6 +136,8 @@
 
     virtual status_t setVoiceVolume(float volume);
 
+    virtual status_t getRenderPosition(uint32_t *halFrames, uint32_t *dspFrames, int output);
+
     // IBinder::DeathRecipient
     virtual     void        binderDied(const wp<IBinder>& who);
 
@@ -526,6 +528,7 @@
                     bool        isSuspended() { return (mSuspended != 0); }
         virtual     String8     getParameters(const String8& keys);
         virtual     void        audioConfigChanged(int event, int param = 0);
+        virtual     status_t    getRenderPosition(uint32_t *halFrames, uint32_t *dspFrames);
 
         struct  stream_type_t {
             stream_type_t()