backend/drm: allocate connector CRTC on lease creation

This was leading to crash in compositors if the wanted connector had no CRTC

backend/drm/drm.c

@@ -1642,8 +1642,8 @@ struct wlr_drm_lease *wlr_drm_create_lease(struct wlr_output **outputs,
 		objects[n_objects++] = conn->id;
 		wlr_log(WLR_DEBUG, "Connector %d", conn->id);
 
-		if (!conn->crtc) {
-			wlr_log(WLR_ERROR, "Connector has no CRTC");
+		if (!drm_connector_alloc_crtc(conn)) {
+			wlr_log(WLR_ERROR, "Failled to allocate connector CRTC");
 			return NULL;
 		}