avcodec/m101: Fix off be 2 error

Fixes: out of array read
Fixes: 15263/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_M101_fuzzer-5728999453491200

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpegSigned-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/m101.c

@@ -61,7 +61,7 @@ static int m101_decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
     stride = AV_RL32(avctx->extradata + 5*4);
 
     if (avctx->pix_fmt == AV_PIX_FMT_YUV422P10)
-        min_stride = (avctx->width + 15) / 16 * 20;
+        min_stride = (avctx->width + 15) / 16 * 40;
 
     if (stride < min_stride || avpkt->size < stride * (uint64_t)avctx->height) {
         av_log(avctx, AV_LOG_ERROR, "stride (%d) is invalid for packet sized %d\n",