net: dsa: realtek: get internal MDIO node by name

The binding docs requires for SMI-connected devices that the switch
must have a child node named "mdio" and with a compatible string of
"realtek,smi-mdio". Meanwile, for MDIO-connected switches, the binding
docs only requires a child node named "mdio".

This patch changes the driver to use the common denominator for both
interfaces, looking for the MDIO node by name, ignoring the compatible
string.
Signed-off-by: Luiz Angelo Daros de Luca <luizluca@gmail.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/dsa/realtek/realtek-smi.c

@@ -333,7 +333,7 @@ static int realtek_smi_setup_mdio(struct dsa_switch *ds)
 	struct device_node *mdio_np;
 	int ret;
 
-	mdio_np = of_get_compatible_child(priv->dev->of_node, "realtek,smi-mdio");
+	mdio_np = of_get_child_by_name(priv->dev->of_node, "mdio");
 	if (!mdio_np) {
 		dev_err(priv->dev, "no MDIO bus node\n");
 		return -ENODEV;