net: fec: Allow the PHY node to be retrieved

As we move towards driver model, it is required to let the FEC driver
know how to properly deal with an Ethernet PHY subnode in the device tree.

For example:

 &fec {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_microsom_enet_ar8035>;
	phy-handle = <&phy>;
 	phy-mode = "rgmii-id";
 	phy-reset-duration = <2>;
 	phy-reset-gpios = <&gpio4 15 GPIO_ACTIVE_LOW>;
 	status = "okay";

	mdio {
		#address-cells = <1>;
		#size-cells = <0>;

		phy: ethernet-phy@0 {
			reg = <0>;
			qca,clk-out-frequency = <125000000>;
		};
	};
 };

Currently the PHY node pointer is incorrectly associated with the
Ethernel controller instead of the PHY node itself.

This causes the PHY properties, such as "qca,clk-out-frequency" in
the example above to not get parsed.

Fix this problem by populating the phy_of_node node.

Suggested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Tested-by: Tom Rini <trini@konsulko.com>
diff --git a/drivers/net/fec_mxc.c b/drivers/net/fec_mxc.c
index 9ae2db0..992180d 100644
--- a/drivers/net/fec_mxc.c
+++ b/drivers/net/fec_mxc.c
@@ -1294,7 +1294,7 @@
 	.read_rom_hwaddr	= fecmxc_read_rom_hwaddr,
 };
 
-static int device_get_phy_addr(struct udevice *dev)
+static int device_get_phy_addr(struct fec_priv *priv, struct udevice *dev)
 {
 	struct ofnode_phandle_args phandle_args;
 	int reg;
@@ -1305,6 +1305,8 @@
 		return -ENODEV;
 	}
 
+	priv->phy_of_node = phandle_args.node;
+
 	reg = ofnode_read_u32_default(phandle_args.node, "reg", 0);
 
 	return reg;
@@ -1315,7 +1317,7 @@
 	struct phy_device *phydev;
 	int addr;
 
-	addr = device_get_phy_addr(dev);
+	addr = device_get_phy_addr(priv, dev);
 #ifdef CONFIG_FEC_MXC_PHYADDR
 	addr = CONFIG_FEC_MXC_PHYADDR;
 #endif
@@ -1325,6 +1327,7 @@
 		return -ENODEV;
 
 	priv->phydev = phydev;
+	priv->phydev->node = priv->phy_of_node;
 	phy_config(phydev);
 
 	return 0;