lavfi/noise: remove get_video_buffer, its redundant now

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

libavfilter/vf_noise.c

@@ -447,7 +447,6 @@ static const AVFilterPad noise_inputs[] = {
     {
         .name             = "default",
         .type             = AVMEDIA_TYPE_VIDEO,
-        .get_video_buffer = ff_null_get_video_buffer,
         .filter_frame     = filter_frame,
         .config_props     = config_input,
     },