avcodec/cfhdenc: Clear dwt_tmp

This occurs on a 32x32 input

Fixes: use of uninitialized value
Fixes: 70897/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_CFHD_fuzzer-5960860961406976

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 9de721de70)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/cfhdenc.c

@@ -285,7 +285,7 @@ static av_cold int cfhd_encode_init(AVCodecContext *avctx)
         s->plane[i].dwt_buf =
             av_calloc(h8 * 8 * w8 * 8, sizeof(*s->plane[i].dwt_buf));
         s->plane[i].dwt_tmp =
-            av_malloc_array(h8 * 8 * w8 * 8, sizeof(*s->plane[i].dwt_tmp));
+            av_calloc(h8 * 8 * w8 * 8, sizeof(*s->plane[i].dwt_tmp));
         if (!s->plane[i].dwt_buf || !s->plane[i].dwt_tmp)
             return AVERROR(ENOMEM);