effect_descriptor_t const correctness

Change-Id: Iad008f20d35a18acf500f773900164552fd0c19e
diff --git a/include/media/AudioSystem.h b/include/media/AudioSystem.h
index 61d62b0..932482b 100644
--- a/include/media/AudioSystem.h
+++ b/include/media/AudioSystem.h
@@ -219,8 +219,8 @@
     static uint32_t getStrategyForStream(audio_stream_type_t stream);
     static audio_devices_t getDevicesForStream(audio_stream_type_t stream);
 
-    static audio_io_handle_t getOutputForEffect(effect_descriptor_t *desc);
-    static status_t registerEffect(effect_descriptor_t *desc,
+    static audio_io_handle_t getOutputForEffect(const effect_descriptor_t *desc);
+    static status_t registerEffect(const effect_descriptor_t *desc,
                                     audio_io_handle_t io,
                                     uint32_t strategy,
                                     int session,