lavfi/anull: remove redundant lines

Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavfilter/af_anull.c

@@ -31,7 +31,6 @@ static const AVFilterPad avfilter_af_anull_inputs[] = {
     {
         .name             = "default",
         .type             = AVMEDIA_TYPE_AUDIO,
-        .get_audio_buffer = ff_null_get_audio_buffer,
     },
     { NULL }
 };
@@ -47,12 +46,7 @@ static const AVFilterPad avfilter_af_anull_outputs[] = {
 AVFilter avfilter_af_anull = {
     .name      = "anull",
     .description = NULL_IF_CONFIG_SMALL("Pass the source unchanged to the output."),
-
-    .priv_size = 0,
-
     .query_formats = ff_query_formats_all,
-
     .inputs    = avfilter_af_anull_inputs,
-
     .outputs   = avfilter_af_anull_outputs,
 };