avformat/matroskaenc: remove bogus prores tag

Fixes: ffmpeg -i input -c:v prores output.mkv
Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavformat/matroskaenc.c

@@ -1699,7 +1699,6 @@ static const AVCodecTag additional_audio_tags[] = {
 };
 
 static const AVCodecTag additional_video_tags[] = {
-    { AV_CODEC_ID_PRORES,    0xFFFFFFFF },
     { AV_CODEC_ID_RV10,      0xFFFFFFFF },
     { AV_CODEC_ID_RV20,      0xFFFFFFFF },
     { AV_CODEC_ID_RV30,      0xFFFFFFFF },