mp_image: do not skip MEL-only Dolby Vision metadata w/EL

Improve the EL check to accept RPUs that indicate EL usage (profiles 4
and 7) if the original bitstream and metadata are MEL-only.

This needs libplacebo commit 9ce8bcff ("util/libav: do not bail on
MEL-only RPUs w/EL").

[FIXME: new API version in libplacebo and API availabilty check]

Author: intelfx

video/mp_image.c

@@ -1095,8 +1095,7 @@ struct mp_image *mp_image_from_av_frame(struct AVFrame *src)
     if (sd) {
 #ifdef PL_HAVE_LAV_DOLBY_VISION
         const AVDOVIMetadata *metadata = (const AVDOVIMetadata *)sd->buf->data;
-        const AVDOVIRpuDataHeader *header = av_dovi_get_header(metadata);
-        if (header->disable_residual_flag) {
+        if (pl_can_map_avdovi_metadata(metadata)) {
             dst->dovi = dovi = av_buffer_alloc(sizeof(struct pl_dovi_metadata));
             MP_HANDLE_OOM(dovi);
 #if PL_API_VER >= 343