drm/nouveau: Disable atomic support on a per-device basis

We now have per-device driver_features, so let's use that
to disable atomic only for pre-nv50.

Cc: Ben Skeggs <bskeggs@redhat.com>
Cc: Lyude Paul <lyude@redhat.com>
Cc: nouveau@lists.freedesktop.org
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/dispnv04/disp.c

@@ -209,7 +209,7 @@ nv04_display_create(struct drm_device *dev)
 	nouveau_display(dev)->fini = nv04_display_fini;
 
 	/* Pre-nv50 doesn't support atomic, so don't expose the ioctls */
-	dev->driver->driver_features &= ~DRIVER_ATOMIC;
+	dev->driver_features &= ~DRIVER_ATOMIC;
 
 	/* Request page flip completion event. */
 	if (drm->nvsw.client) {