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/media/libmedia/AudioEffect.cpp b/media/libmedia/AudioEffect.cpp
index a242846..bfa093d 100644
--- a/media/libmedia/AudioEffect.cpp
+++ b/media/libmedia/AudioEffect.cpp
@@ -412,7 +412,8 @@
     return af->queryEffect(index, descriptor);
 }
 
-status_t AudioEffect::getEffectDescriptor(effect_uuid_t *uuid, effect_descriptor_t *descriptor)
+status_t AudioEffect::getEffectDescriptor(effect_uuid_t *uuid,
+        effect_descriptor_t *descriptor) /*const*/
 {
     const sp<IAudioFlinger>& af = AudioSystem::get_audio_flinger();
     if (af == 0) return PERMISSION_DENIED;