Move control block mName to createTrack() output

This is part of a series of CLs to clean up the shared memory
control block, by removing any fields that don't have to be there.

Change-Id: I6e51003a1293b6800258c31b22cff2eba42162e7
diff --git a/services/audioflinger/PlaybackTracks.h b/services/audioflinger/PlaybackTracks.h
index 8b7433c..628f5af 100644
--- a/services/audioflinger/PlaybackTracks.h
+++ b/services/audioflinger/PlaybackTracks.h
@@ -106,6 +106,7 @@
     bool isInvalid() const { return mIsInvalid; }
     virtual bool isTimedTrack() const { return false; }
     bool isFastTrack() const { return (mFlags & IAudioFlinger::TRACK_FAST) != 0; }
+    int fastIndex() const { return mFastIndex; }
 
 protected: