net: arc_emac: Fix memleak in arc_mdio_probe

When devm_gpiod_get_optional() fails, bus should be
freed just like when of_mdiobus_register() fails.

Fixes: 1bddd96c ("net: arc_emac: support the phy reset for emac driver")
Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/arc/emac_mdio.c

@@ -153,6 +153,7 @@ int arc_mdio_probe(struct arc_emac_priv *priv)
 	if (IS_ERR(data->reset_gpio)) {
 		error = PTR_ERR(data->reset_gpio);
 		dev_err(priv->dev, "Failed to request gpio: %d\n", error);
+		mdiobus_free(bus);
 		return error;
 	}