Fix type error in AudioTrack::processAudioBuffer

It returned a bool instead of nsecs_t

Change-Id: If0c096dac411afc0a4142ec1e59c1fdd36d4867c
diff --git a/media/libmedia/AudioTrack.cpp b/media/libmedia/AudioTrack.cpp
index 33c4462..00f4640 100644
--- a/media/libmedia/AudioTrack.cpp
+++ b/media/libmedia/AudioTrack.cpp
@@ -1238,7 +1238,8 @@
         if (tryCounter < 0) {
             ALOGE("did not receive expected priority boost on time");
         }
-        return true;
+        // Run again immediately
+        return 0;
     }
 
     // Can only reference mCblk while locked