net: mdiobus: fix fwnode_mdbiobus_register() fallback case

The fallback case of fwnode_mdbiobus_register()
(relevant for !CONFIG_FWNODE_MDIO) was defined with wrong
argument name, causing a compilation error. Fix that.
Signed-off-by: Marcin Wojtas <mw@semihalf.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/fwnode_mdio.h

@@ -40,7 +40,7 @@ static inline int fwnode_mdiobus_register(struct mii_bus *bus,
 	 * This way, we don't have to keep compat bits around in drivers.
 	 */
 
-	return mdiobus_register(mdio);
+	return mdiobus_register(bus);
 }
 #endif