drm/virtio: Enable fb damage clips property for the primary plane

Christian Hergert reports that the driver doesn't enable the property and
that leads to always doing a full plane update, even when the driver does
support damage clipping for the primary plane.

Don't enable it for the cursor plane, because its .atomic_update callback
doesn't handle damage clips.

Reported-by: Christian Hergert <chergert@redhat.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230310125943.912514-1-javierm@redhat.com