avcodec/hq_hqadsp: Fix runtime error: signed integer overflow: 80359 * 30274 cannot be represented in type 'int'

Fixes: 1507/clusterfuzz-testcase-minimized-4955228300378112

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