Close RTT streams on destroy

The closeRttStreams method was apparently never called before. Add a
call to it upon destroying the call.

Change-Id: I0697610f8d2a3245d544b5ebf7fbfcba3bd33d82
Fixes: 121004839
Test: manual
diff --git a/src/com/android/server/telecom/Call.java b/src/com/android/server/telecom/Call.java
index 6784d2b..2a7b25d 100644
--- a/src/com/android/server/telecom/Call.java
+++ b/src/com/android/server/telecom/Call.java
@@ -673,6 +673,7 @@
             mCallerInfo.cachedPhotoIcon = null;
             mCallerInfo.cachedPhoto = null;
         }
+        closeRttStreams();
 
         Log.addEvent(this, LogUtils.Events.DESTROYED);
     }