vaapi: Disable Wayland if no libdrm

vaapi: Disable Wayland if no libdrm

Platform wise, is not possible, as far as I known, to have Wayland
without kernel's DRM. Though, it's possible to configure
gstreamer-vaapi without DRM but Wayland support, with the enhanced
handling of dmabuf in vaapisink for Wayland, vaapisink will always
fail. Given both issues, configuration with no DRM but Wayland, makes
things more complex, and a simpler approach is to refuse that
configuration.

This patch disables Wayland support if there isn't DRM support. Also,
it disables the display test for Wayland, relying only on DRM and
X11.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1606>