lavd/lavfi: do not set the channel layout list.

The list was set to avfilter_all_channel_layouts,
which is really all common channel layouts.
Not setting it leaves an empty list,
which now means really all.

libavdevice/lavfi.c

@@ -211,10 +211,8 @@ av_cold static int lavfi_read_header(AVFormatContext *avctx)
                                                   AV_SAMPLE_FMT_S32,
                                                   AV_SAMPLE_FMT_FLT,
                                                   AV_SAMPLE_FMT_DBL, -1 };
-            const int64_t *chlayouts = avfilter_all_channel_layouts;
             AVABufferSinkParams *abuffersink_params = av_abuffersink_params_alloc();
             abuffersink_params->sample_fmts = sample_fmts;
-            abuffersink_params->channel_layouts = chlayouts;
 
             ret = avfilter_graph_create_filter(&sink, abuffersink,
                                                inout->name, NULL,