avfilter: fix plane validity checks

Fixes out of array accesses

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
static int query_formats(AVFilterContext *ctx)
{
    static const enum AVPixelFormat pix_fmts[] = {
        AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV422P,
        AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV411P,
        AV_PIX_FMT_YUV410P, AV_PIX_FMT_YUV440P,
        AV_PIX_FMT_RGB24,   AV_PIX_FMT_BGR24,
        AV_PIX_FMT_GRAY8,
        AV_PIX_FMT_NONE
    };
    ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
    return 0;
}

static int query_formats(AVFilterContext *ctx)
{
    static const enum AVPixelFormat pix_fmts[] = {
        AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUV422P,
        AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV411P,
        AV_PIX_FMT_YUV410P, AV_PIX_FMT_YUV440P,
        AV_PIX_FMT_RGB24,   AV_PIX_FMT_BGR24,
        AV_PIX_FMT_GRAY8,
        AV_PIX_FMT_NONE
    };
    ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
    return 0;
}
