Declare more IAudioFlinger methods const

This is just documentation, as C++ method const-ness doesn't mean anything
for a binder API.  Instead, here const means "no side effects".

Change-Id: Iaa9cd2fe477db10ae9a40cac4f79f0faa9b4e5e6
diff --git a/include/media/AudioEffect.h b/include/media/AudioEffect.h
index 7b0b443..4c57ed2 100644
--- a/include/media/AudioEffect.h
+++ b/include/media/AudioEffect.h
@@ -108,7 +108,8 @@
      * Returned value
      *   *descriptor updated with effect descriptor
      */
-    static status_t getEffectDescriptor(effect_uuid_t *uuid, effect_descriptor_t *descriptor);
+    static status_t getEffectDescriptor(effect_uuid_t *uuid,
+                                        effect_descriptor_t *descriptor) /*const*/;
 
 
     /*