spu: remove bogus VLC_UNUSED

src/video_output/vout_subpictures.c

@@ -175,9 +175,9 @@ static picture_t *spu_new_video_buffer(filter_t *filter)
 {
     const video_format_t *fmt = &filter->fmt_out.video;
 
-    VLC_UNUSED(filter);
     return picture_NewFromFormat(fmt);
 }
+
 static void spu_del_video_buffer(filter_t *filter, picture_t *picture)
 {
     VLC_UNUSED(filter);