pmp: convert to new channel layout API

Signed-off-by: Vittorio Giovara <vittorio.giovara@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>

libavformat/pmpdec.c

@@ -119,7 +119,7 @@ static int pmp_header(AVFormatContext *s)
             return AVERROR(ENOMEM);
         ast->codecpar->codec_type  = AVMEDIA_TYPE_AUDIO;
         ast->codecpar->codec_id    = audio_codec_id;
-        ast->codecpar->channels    = channels;
+        ast->codecpar->ch_layout.nb_channels = channels;
         ast->codecpar->sample_rate = srate;
         avpriv_set_pts_info(ast, 32, 1, srate);
     }