net: mdio: provide shim implementation of devm_of_mdiobus_register

Similar to the way in which of_mdiobus_register() has a fallback to the
non-DT based mdiobus_register() when CONFIG_OF is not set, we can create
a shim for the device-managed devm_of_mdiobus_register() which calls
devm_mdiobus_register() and discards the struct device_node *.

In particular, this solves a build issue with the qca8k DSA driver which
uses devm_of_mdiobus_register and can be compiled without CONFIG_OF.
Reported-by: NRandy Dunlap <rdunlap@infradead.org>
Signed-off-by: NVladimir Oltean <olteanv@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Reviewed-by: NAndrew Lunn <andrew@lunn.ch>
Reviewed-by: NFlorian Fainelli <f.fainelli@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/of_mdio.h

@@ -72,6 +72,13 @@ static inline int of_mdiobus_register(struct mii_bus *mdio, struct device_node *
 	return mdiobus_register(mdio);
 }
 
+static inline int devm_of_mdiobus_register(struct device *dev,
+					   struct mii_bus *mdio,
+					   struct device_node *np)
+{
+	return devm_mdiobus_register(dev, mdio);
+}
+
 static inline struct mdio_device *of_mdio_find_device(struct device_node *np)
 {
 	return NULL;