avcodec/utils: correct align value for interplay

Fixes out of array access
Fixes: 452/fuzz-1-ffmpeg_VIDEO_AV_CODEC_ID_INTERPLAY_VIDEO_fuzzer

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/targets/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
unsigned int avpriv_toupper4(unsigned int x)
{
    return av_toupper(x & 0xFF) +
          (av_toupper((x >>  8) & 0xFF) << 8)  +
          (av_toupper((x >> 16) & 0xFF) << 16) +
((unsigned)av_toupper((x >> 24) & 0xFF) << 24);
}

unsigned int avpriv_toupper4(unsigned int x)
{
    return av_toupper(x & 0xFF) +
          (av_toupper((x >>  8) & 0xFF) << 8)  +
          (av_toupper((x >> 16) & 0xFF) << 16) +
((unsigned)av_toupper((x >> 24) & 0xFF) << 24);
}
