mlpdec: supress layout mismatch warnings for 2 ch upmixed mono

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/mlpdec.c

@@ -340,6 +340,8 @@ static int read_major_sync(MLPDecodeContext *m, GetBitContext *gb)
         if (m->avctx->channels<=2 && m->avctx->channel_layout == AV_CH_LAYOUT_MONO && m->max_decoded_substream == 1) {
             av_log(m->avctx, AV_LOG_DEBUG, "Mono stream with 2 substreams, ignoring 2nd\n");
             m->max_decoded_substream = 0;
+            if (m->avctx->channels==2)
+                m->avctx->channel_layout = AV_CH_LAYOUT_STEREO;
         }
         if (m->avctx->channels &&
             !m->avctx->request_channels && !m->avctx->request_channel_layout &&