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>
enum AVPixelFormat avpriv_find_pix_fmt(const PixelFormatTag *tags,
                                       unsigned int fourcc)
{
    while (tags->pix_fmt >= 0) {
        if (tags->fourcc == fourcc)
            return tags->pix_fmt;
        tags++;
    }
    return AV_PIX_FMT_NONE;
}

enum AVPixelFormat avpriv_find_pix_fmt(const PixelFormatTag *tags,
                                       unsigned int fourcc)
{
    while (tags->pix_fmt >= 0) {
        if (tags->fourcc == fourcc)
            return tags->pix_fmt;
        tags++;
    }
    return AV_PIX_FMT_NONE;
}
