avcodec/libcodec2: Remove dead channel count check

This encoder has AVCodec.ch_layouts set, so that this is checked
generically.

Reviewed-by: Tomas Härdin <tjoppen@acc.umu.se>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavcodec/libcodec2.c

@@ -105,7 +105,6 @@ static av_cold int libcodec2_init_encoder(AVCodecContext *avctx)
 
     //will need to be smarter once we get wideband support
     if (avctx->sample_rate != 8000 ||
-        avctx->ch_layout.nb_channels != 1 ||
         avctx->sample_fmt != AV_SAMPLE_FMT_S16) {
         av_log(avctx, AV_LOG_ERROR, "only 8 kHz 16-bit mono allowed\n");
         return AVERROR(EINVAL);