drm: fix oops in drm_atomic_set_crtc_for_connector

crtc can be NULL. connector, extracted from conn_state, can't.

Fixes: e3aae683 ("drm: convert drm_atomic_uapi.c to new debug helpers")
Signed-off-by: Simon Ser <contact@emersion.fr>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/7xhyNYrWtzUIt3HNrWfi9iScW0k475RZiKNfF5TbPs@cp4-web-031.plabs.ch

drivers/gpu/drm/drm_atomic_uapi.c

@@ -334,12 +334,12 @@ drm_atomic_set_crtc_for_connector(struct drm_connector_state *conn_state,
 		drm_connector_get(conn_state->connector);
 		conn_state->crtc = crtc;
 
-		drm_dbg_atomic(crtc->dev,
+		drm_dbg_atomic(connector->dev,
 			       "Link [CONNECTOR:%d:%s] state %p to [CRTC:%d:%s]\n",
 			       connector->base.id, connector->name,
 			       conn_state, crtc->base.id, crtc->name);
 	} else {
-		drm_dbg_atomic(crtc->dev,
+		drm_dbg_atomic(connector->dev,
 			       "Link [CONNECTOR:%d:%s] state %p to [NOCRTC]\n",
 			       connector->base.id, connector->name,
 			       conn_state);