drm/nouveau/disp: Set drm_mode_config_funcs.atomic_(check|commit)

drm/nouveau/disp: Set drm_mode_config_funcs.atomic_(check|commit)

Apparently we never actually filled these in, despite the fact that we do
in fact technically support atomic modesetting.

Since not having these filled in causes us to potentially forget to disable
fbdev and friends during suspend/resume, let's fix it.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: stable@vger.kernel.org
Reviewed-by: Dave Airlie <airlied@redhat.com>
Link: https://patch.msgid.link/20260121191320.210342-1-lyude@redhat.com