Re-enable fast track for ToneGenerator

Change-Id: If4152169778df124c750dc45023322ee23c80587
diff --git a/media/libmedia/ToneGenerator.cpp b/media/libmedia/ToneGenerator.cpp
index eac71c5..253602d 100644
--- a/media/libmedia/ToneGenerator.cpp
+++ b/media/libmedia/ToneGenerator.cpp
@@ -1024,7 +1024,7 @@
                       AUDIO_FORMAT_PCM_16_BIT,
                       AUDIO_CHANNEL_OUT_MONO,
                       0,    // frameCount
-                      AUDIO_OUTPUT_FLAG_NONE,
+                      AUDIO_OUTPUT_FLAG_FAST,
                       audioCallback,
                       this, // user
                       0,    // notificationFrames