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>
int avcodec_enum_to_chroma_pos(int *xpos, int *ypos, enum AVChromaLocation pos)
{
    if (pos <= AVCHROMA_LOC_UNSPECIFIED || pos >= AVCHROMA_LOC_NB)
        return AVERROR(EINVAL);
    pos--;

    *xpos = (pos&1) * 128;
    *ypos = ((pos>>1)^(pos<4)) * 128;

    return 0;
}

int avcodec_enum_to_chroma_pos(int *xpos, int *ypos, enum AVChromaLocation pos)
{
    if (pos <= AVCHROMA_LOC_UNSPECIFIED || pos >= AVCHROMA_LOC_NB)
        return AVERROR(EINVAL);
    pos--;

    *xpos = (pos&1) * 128;
    *ypos = ((pos>>1)^(pos<4)) * 128;

    return 0;
}
