ffplay: do not set redundant channel count on abuffersink.

fftools/ffplay.c

@@ -2008,7 +2008,7 @@ static int configure_audio_filters(VideoState *is, const char *afilters, int for
 
     if (force_output_format) {
         channel_layouts[0] = is->audio_tgt.channel_layout;
-        channels       [0] = is->audio_tgt.channels;
+        channels       [0] = is->audio_tgt.channel_layout ? -1 : is->audio_tgt.channels;
         sample_rates   [0] = is->audio_tgt.freq;
         if ((ret = av_opt_set_int(filt_asink, "all_channel_counts", 0, AV_OPT_SEARCH_CHILDREN)) < 0)
             goto end;