coreaudio: Always return 0 in handle_voice_change

handle_voice_change() is a CoreAudio callback function as of CoreAudio type
AudioObjectPropertyListenerProc, and for the latter MacOSX.sdk/System/
Library/Frameworks/CoreAudio.framework/Headers/AudioHardware.h
says "The return value is currently unused and should always be 0.".

Signed-off-by: Akihiko Odaki <akihiko.odaki@gmail.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20220306123410.61063-1-akihiko.odaki@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

audio/coreaudio.c

@@ -545,7 +545,6 @@ static OSStatus handle_voice_change(
     const AudioObjectPropertyAddress *in_addresses,
     void *in_client_data)
 {
-    OSStatus status;
     coreaudioVoiceOut *core = in_client_data;
 
     qemu_mutex_lock_iothread();
@@ -554,13 +553,12 @@ static OSStatus handle_voice_change(
         fini_out_device(core);
     }
 
-    status = init_out_device(core);
-    if (!status) {
+    if (!init_out_device(core)) {
         update_device_playback_state(core);
     }
 
     qemu_mutex_unlock_iothread();
-    return status;
+    return 0;
 }
 
 static int coreaudio_init_out(HWVoiceOut *hw, struct audsettings *as,