avcodec/mv30: check mode_size vs. input space

Fixes: Timeout (longer than my patience vs 1sec)
Fixes: 22984/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MV30_fuzzer-5630021988515840

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

libavcodec/mv30.c

@@ -410,6 +410,9 @@ static int decode_intra(AVCodecContext *avctx, GetBitContext *gb, AVFrame *frame
     int ret;
 
     mgb = *gb;
+    if (get_bits_left(gb) < s->mode_size * 8)
+        return AVERROR_INVALIDDATA;
+
     skip_bits_long(gb, s->mode_size * 8);
 
     linesize[0] = frame->linesize[0];