net: dsa: mv88e6xxx: chip: Add of_node_put() before return

Each iteration of for_each_available_child_of_node puts the previous
node, but in the case of a return from the middle of the loop, there is
no put, thus causing a memory leak. Hence add an of_node_put before the
return.
Issue found with Coccinelle.

Signed-off-by: Nishka Dasgupta <nishkadg.linux@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/mv88e6xxx/chip.c

@@ -2721,6 +2721,7 @@ static int mv88e6xxx_mdios_register(struct mv88e6xxx_chip *chip,
 			err = mv88e6xxx_mdio_register(chip, child, true);
 			if (err) {
 				mv88e6xxx_mdios_unregister(chip);
+				of_node_put(child);
 				return err;
 			}
 		}