Add FIXME to deprecate AudioTrack::getMinFrameCount()

Continuation of previous change, for all APIs that assume a route

Change-Id: Ia1315032cf6366f428db342b16b2e1c3b574f407
diff --git a/include/media/AudioTrack.h b/include/media/AudioTrack.h
index cc7acbc..0d10e31 100644
--- a/include/media/AudioTrack.h
+++ b/include/media/AudioTrack.h
@@ -125,6 +125,7 @@
      *  - BAD_VALUE: unsupported configuration
      * frameCount is guaranteed to be non-zero if status is NO_ERROR,
      * and is undefined otherwise.
+     * FIXME This API assumes a route, and so should be deprecated.
      */
 
     static status_t getMinFrameCount(size_t* frameCount,