Revert "Use AudioTrack::event_type not int in callback"

This reverts commit 2225e4b7049fa3fb9d39a068b8268b63c952d7c1
diff --git a/include/media/AudioTrack.h b/include/media/AudioTrack.h
index 4fc7f2d..df30e8c 100644
--- a/include/media/AudioTrack.h
+++ b/include/media/AudioTrack.h
@@ -99,7 +99,7 @@
      *          - EVENT_BUFFER_END: unused.
      */
 
-    typedef void (*callback_t)(event_type event, void* user, void *info);
+    typedef void (*callback_t)(int event, void* user, void *info);
 
     /* Returns the minimum frame count required for the successful creation of
      * an AudioTrack object.