drm/mode: rework drm_mode_object_put to drm_mode_object_unregister.

This changes the code to handle being called multiple times without
side effects. The new names seems more suitable for what it does.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_modes.c

@@ -98,7 +98,7 @@ void drm_mode_destroy(struct drm_device *dev, struct drm_display_mode *mode)
 	if (!mode)
 		return;
 
-	drm_mode_object_put(dev, &mode->base);
+	drm_mode_object_unregister(dev, &mode->base);
 
 	kfree(mode);
 }