Fix freeze on pause

isOffloaded() tries to lock mLock again. We should be calling isOffloaded_l()
b/13394633

Change-Id: I155be6fee937f894d8e6c974e593223ab6014ade
diff --git a/media/libmedia/AudioTrack.cpp b/media/libmedia/AudioTrack.cpp
index 3217171..ae47201 100644
--- a/media/libmedia/AudioTrack.cpp
+++ b/media/libmedia/AudioTrack.cpp
@@ -555,7 +555,7 @@
     mProxy->interrupt();
     mAudioTrack->pause();
 
-    if (isOffloaded()) {
+    if (isOffloaded_l()) {
         if (mOutput != 0) {
             uint32_t halFrames;
             // OffloadThread sends HAL pause in its threadLoop.. time saved