Rename setStreamOutput to invalidateStream

And simplify by removing the unused I/O handle parameter 'output'.

Change-Id: Ie9c4df17a7378066312d4ed8790fda7a9125c95e
diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index 21d05d4..c2b516b 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -182,7 +182,7 @@
 
     virtual status_t closeInput(audio_io_handle_t input);
 
-    virtual status_t setStreamOutput(audio_stream_type_t stream, audio_io_handle_t output);
+    virtual status_t invalidateStream(audio_stream_type_t stream);
 
     virtual status_t setVoiceVolume(float volume);