drm/dp/mst: constify drm_dp_mst_topology_cbs structures

The drm_dp_mst_topology_cbs structures are never modified, so declare them
as const.

Done with the help of Coccinelle.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
diff --git a/drivers/gpu/drm/i915/intel_dp_mst.c b/drivers/gpu/drm/i915/intel_dp_mst.c
index e8d369d..9ae1a4f 100644
--- a/drivers/gpu/drm/i915/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/intel_dp_mst.c
@@ -512,7 +512,7 @@
 	drm_kms_helper_hotplug_event(dev);
 }
 
-static struct drm_dp_mst_topology_cbs mst_cbs = {
+static const struct drm_dp_mst_topology_cbs mst_cbs = {
 	.add_connector = intel_dp_add_mst_connector,
 	.register_connector = intel_dp_register_mst_connector,
 	.destroy_connector = intel_dp_destroy_mst_connector,
diff --git a/drivers/gpu/drm/radeon/radeon_dp_mst.c b/drivers/gpu/drm/radeon/radeon_dp_mst.c
index 94323f5..8a02225 100644
--- a/drivers/gpu/drm/radeon/radeon_dp_mst.c
+++ b/drivers/gpu/drm/radeon/radeon_dp_mst.c
@@ -329,7 +329,7 @@
 	drm_kms_helper_hotplug_event(dev);
 }
 
-struct drm_dp_mst_topology_cbs mst_cbs = {
+const struct drm_dp_mst_topology_cbs mst_cbs = {
 	.add_connector = radeon_dp_add_mst_connector,
 	.register_connector = radeon_dp_register_mst_connector,
 	.destroy_connector = radeon_dp_destroy_mst_connector,