dsa: fix for_each_child.cocci warnings

For_each_available_child_of_node should have of_node_put() before
return around line 423.

Generated by: scripts/coccinelle/iterators/for_each_child.cocci

CC: Alexander Lobakin <alobakin@pm.me>
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: kernel test robot <lkp@intel.com>
Signed-off-by: Julia Lawall <julia.lawall@inria.fr>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/microchip/ksz_common.c

@@ -419,8 +419,10 @@ int ksz_switch_register(struct ksz_device *dev,
 				if (of_property_read_u32(port, "reg",
 							 &port_num))
 					continue;
-				if (!(dev->port_mask & BIT(port_num)))
+				if (!(dev->port_mask & BIT(port_num))) {
+					of_node_put(port);
 					return -EINVAL;
+				}
 				of_get_phy_mode(port,
 						&dev->ports[port_num].interface);
 			}