devlink: update the code in netns move to latest helpers

devlink_pernet_pre_exit() is the only obvious place which takes
the instance lock without using the devl_ helpers. Update the code
and move the error print after releasing the reference
(having unlock and put together feels slightly idiomatic).
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/devlink/core.c

@@ -299,15 +299,16 @@ static void __net_exit devlink_pernet_pre_exit(struct net *net)
 	 */
 	devlinks_xa_for_each_registered_get(net, index, devlink) {
 		WARN_ON(!(devlink->features & DEVLINK_F_RELOAD));
-		mutex_lock(&devlink->lock);
+		devl_lock(devlink);
 		err = devlink_reload(devlink, &init_net,
 				     DEVLINK_RELOAD_ACTION_DRIVER_REINIT,
 				     DEVLINK_RELOAD_LIMIT_UNSPEC,
 				     &actions_performed, NULL);
-		mutex_unlock(&devlink->lock);
+		devl_unlock(devlink);
+		devlink_put(devlink);
+
 		if (err && err != -EOPNOTSUPP)
 			pr_warn("Failed to reload devlink instance into init_net\n");
-		devlink_put(devlink);
 	}
 }