Fix error handling in AudioSystem::getOutputForEffect

and AudioPolicyService::getOutputForEffect.
The conventional error value for audio_io_handle_t is 0,
not a status_t cast to audio_io_handle_t.

Change-Id: I34b3fd1a50f3fa1cbf39f32eea1911112a4e094a
diff --git a/media/libmedia/AudioSystem.cpp b/media/libmedia/AudioSystem.cpp
index 9a76111..cf7dfef 100644
--- a/media/libmedia/AudioSystem.cpp
+++ b/media/libmedia/AudioSystem.cpp
@@ -719,7 +719,8 @@
 audio_io_handle_t AudioSystem::getOutputForEffect(const effect_descriptor_t *desc)
 {
     const sp<IAudioPolicyService>& aps = AudioSystem::get_audio_policy_service();
-    if (aps == 0) return PERMISSION_DENIED;
+    // FIXME change return type to status_t, and return PERMISSION_DENIED here
+    if (aps == 0) return 0;
     return aps->getOutputForEffect(desc);
 }