net: dsa: microchip: lan937x: fix reference count leak in lan937x_mdio_register()

This node pointer is returned by of_find_compatible_node() with
refcount incremented in this function. of_node_put() on it before
exitting this function.

Fixes: c9cd961c ("net: dsa: microchip: lan937x: add interrupt support for port phy link")
Signed-off-by: Sun Ke <sunke32@huawei.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20220908040226.871690-1-sunke32@huawei.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/dsa/microchip/lan937x_main.c

@@ -238,8 +238,10 @@ static int lan937x_mdio_register(struct ksz_device *dev)
 	ds->slave_mii_bus = bus;
 
 	ret = lan937x_irq_phy_setup(dev);
-	if (ret)
+	if (ret) {
+		of_node_put(mdio_np);
 		return ret;
+	}
 
 	ret = devm_of_mdiobus_register(ds->dev, bus, mdio_np);
 	if (ret) {