Fix issue 1795088       Improve audio routing code

Initial commit for review.
Integrated comments after patch set 1 review.
Fixed lockup in AudioFlinger::ThreadBase::exit()
Fixed lockup when playing tone with AudioPlocyService startTone()
diff --git a/media/libmedia/JetPlayer.cpp b/media/libmedia/JetPlayer.cpp
index 586aacb..ee9e1d8 100644
--- a/media/libmedia/JetPlayer.cpp
+++ b/media/libmedia/JetPlayer.cpp
@@ -99,7 +99,7 @@
     mAudioTrack->set(AudioSystem::MUSIC,  //TODO parametrize this
             pLibConfig->sampleRate,
             1, // format = PCM 16bits per sample,
-            pLibConfig->numChannels,
+            (pLibConfig->numChannels == 2) ? AudioSystem::CHANNEL_OUT_STEREO : AudioSystem::CHANNEL_OUT_MONO,
             mTrackBufferSize,
             0);