avcodec/v210dec: move the stride read after its fully initialized

Fixes: out of array read
Fixes: 19129/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_V210_fuzzer-5068171023482880
Maybe fixes: 19130/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_V210_fuzzer-5637264407527424

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

libavcodec/v210dec.c

@@ -153,7 +153,6 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
         int aligned_width = ((avctx->width + 47) / 48) * 48;
         stride = aligned_width * 8 / 3;
     }
-    td.stride = stride;
 
     if (avpkt->size < stride * avctx->height) {
         if ((((avctx->width + 23) / 24) * 24 * 8) / 3 * avctx->height == avpkt->size) {
@@ -166,6 +165,7 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
             return AVERROR_INVALIDDATA;
         }
     }
+    td.stride = stride;
     if (   avctx->codec_tag == MKTAG('C', '2', '1', '0')
         && avpkt->size > 64
         && AV_RN32(psrc) == AV_RN32("INFO")