drm: connector->dpms is not optional

We always register the DPMS property, it's really a fundamental
part of a display driver. So don't check whether the vfunc is there,
it's non-optional

Yes I've audited all the almost 100 drm_connector_funcs we have, no
one botched this ;-)

Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1449218769-16577-19-git-send-email-daniel.vetter@ffwll.ch
Reviewed-by: Thierry Reding <treding@nvidia.com>

drivers/gpu/drm/drm_crtc.c

@@ -4785,9 +4785,7 @@ static int drm_mode_connector_set_obj_prop(struct drm_mode_object *obj,
 
 	/* Do DPMS ourselves */
 	if (property == connector->dev->mode_config.dpms_property) {
-		ret = 0;
-		if (connector->funcs->dpms)
-			ret = (*connector->funcs->dpms)(connector, (int)value);
+		ret = (*connector->funcs->dpms)(connector, (int)value);
 	} else if (connector->funcs->set_property)
 		ret = connector->funcs->set_property(connector, property, value);