Revert "mjpegenc: disable huffman coding with AMV"

This was the wrong patch

This reverts commit 7f9b492d.

libavcodec/mpegvideo_enc.c

@@ -399,9 +399,6 @@ FF_ENABLE_DEPRECATION_WARNINGS
         return AVERROR(EINVAL);
     }
 
-    if (s->huffman && avctx->codec_id == AV_CODEC_ID_AMV)
-        s->huffman = 0;
-
     if (s->intra_dc_precision > (avctx->codec_id == AV_CODEC_ID_MPEG2VIDEO ? 3 : 0)) {
         av_log(avctx, AV_LOG_ERROR, "intra dc precision too large\n");
         return AVERROR(EINVAL);