vdpau: fail context create if driver does not support video

not all drivers support this, and forcing them to implement stubs
is not how gallium works

cc: mesa-stable

Reviewed-by: David Rosca <david.rosca@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31736>

src/gallium/frontends/vdpau/device.c

@@ -76,6 +76,12 @@ vdp_imp_device_create_x11(Display *display, int screen, VdpDevice *device,
    }
 
    pscreen = dev->vscreen->pscreen;
+   /* video cannot work if these are not supported */
+   if (!pscreen->get_video_param || !pscreen->is_video_format_supported) {
+      ret = VDP_STATUS_RESOURCES;
+      goto no_vscreen;
+   }
+
    dev->context = pipe_create_multimedia_context(pscreen);
    if (!dev->context) {
       ret = VDP_STATUS_RESOURCES;