net: bridge: make kobj_type structure constant

Since commit ee6d3dd4 ("driver core: make kobj_type constant.")
the driver core allows the usage of const struct kobj_type.

Take advantage of this to constify the structure definition to prevent
modification at runtime.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/bridge/br_if.c

@@ -269,7 +269,7 @@ static void brport_get_ownership(const struct kobject *kobj, kuid_t *uid, kgid_t
 	net_ns_get_ownership(dev_net(p->dev), uid, gid);
 }
 
-static struct kobj_type brport_ktype = {
+static const struct kobj_type brport_ktype = {
 #ifdef CONFIG_SYSFS
 	.sysfs_ops = &brport_sysfs_ops,
 #endif