Simplify AudioTrack::restoreTrack_l()

Remove CBLK_RESTORING and CBLK_RESTORED from control block flags,
for AudioTrack only.  They are still used by AudioRecord.

This is part of a series to clean up the control block.

Change-Id: Iae4798f5b527c492bdaf789987ff3a1dadd0cb37
diff --git a/include/media/AudioTrack.h b/include/media/AudioTrack.h
index 5f235cb..6e88032 100644
--- a/include/media/AudioTrack.h
+++ b/include/media/AudioTrack.h
@@ -509,7 +509,7 @@
     float                   mSendLevel;
     uint32_t                mFrameCount;
 
-    audio_track_cblk_t*     mCblk;
+    audio_track_cblk_t*     mCblk;                  // re-load after mLock.unlock()
     audio_format_t          mFormat;
     audio_stream_type_t     mStreamType;
     uint8_t                 mChannelCount;
@@ -548,7 +548,6 @@
     // It is OK to lock only mCblk->lock.
     mutable Mutex           mLock;
 
-    status_t                mRestoreStatus;
     bool                    mIsTimed;
     int                     mPreviousPriority;          // before start()
     SchedPolicy             mPreviousSchedulingGroup;