drm: Use const data when creating blob properties

Creating a blob property will always copy the input data so the data
that is passed in can be const.

Signed-off-by: Thierry Reding <treding@nvidia.com>
diff --git a/include/drm/drm_dp_mst_helper.h b/include/drm/drm_dp_mst_helper.h
index 338fc10..fdcd7f2 100644
--- a/include/drm/drm_dp_mst_helper.h
+++ b/include/drm/drm_dp_mst_helper.h
@@ -371,7 +371,7 @@
 struct drm_dp_mst_topology_mgr;
 struct drm_dp_mst_topology_cbs {
 	/* create a connector for a port */
-	struct drm_connector *(*add_connector)(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port, char *path);
+	struct drm_connector *(*add_connector)(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port, const char *path);
 	void (*destroy_connector)(struct drm_dp_mst_topology_mgr *mgr,
 				  struct drm_connector *connector);
 	void (*hotplug)(struct drm_dp_mst_topology_mgr *mgr);