audioflinger: fix reused audio patch resource release

Add missing explicit release of audio HAL patch
when a patch is created reusing the same patch handle but
the source or sink devices are not on the same HW module.

Bug: 28953359

Change-Id: Ib751a4b5b2badd745f3b43e69734dd6a3e60eabe
diff --git a/services/audioflinger/PatchPanel.h b/services/audioflinger/PatchPanel.h
index e31179c..16ec278 100644
--- a/services/audioflinger/PatchPanel.h
+++ b/services/audioflinger/PatchPanel.h
@@ -62,12 +62,24 @@
 
         struct audio_patch              mAudioPatch;
         audio_patch_handle_t            mHandle;
+        // handle for audio HAL patch handle present only when the audio HAL version is >= 3.0
         audio_patch_handle_t            mHalHandle;
+        // below members are used by a software audio patch connecting a source device from a
+        // given audio HW module to a sink device on an other audio HW module.
+        // playback thread created by createAudioPatch() and released by clearPatchConnections() if
+        // no existing playback thread can be used by the software patch
         sp<PlaybackThread>              mPlaybackThread;
+        // audio track created by createPatchConnections() and released by clearPatchConnections()
         sp<PlaybackThread::PatchTrack>  mPatchTrack;
+        // record thread created by createAudioPatch() and released by clearPatchConnections()
         sp<RecordThread>                mRecordThread;
+        // audio record created by createPatchConnections() and released by clearPatchConnections()
         sp<RecordThread::PatchRecord>   mPatchRecord;
+        // handle for audio patch connecting source device to record thread input.
+        // created by createPatchConnections() and released by clearPatchConnections()
         audio_patch_handle_t            mRecordPatchHandle;
+        // handle for audio patch connecting playback thread output to sink device
+        // created by createPatchConnections() and released by clearPatchConnections()
         audio_patch_handle_t            mPlaybackPatchHandle;
 
     };