* ENETC ethernet device tree bindings

Depending on board design and ENETC port type (internal or
external) there are two supported link modes specified by
below device tree bindings.

Required properties:

- reg		: Specifies PCIe Device Number and Function
		  Number of the ENETC endpoint device, according
		  to parent node bindings.
- compatible	: Should be "fsl,enetc".

1) The ENETC external port is connected to a MDIO configurable phy:

In this case, the ENETC node should include a "mdio" sub-node
that in turn should contain the "ethernet-phy" node describing the
external phy.  Below properties are required, their bindings
already defined in ethernet.txt or phy.txt, under
Documentation/devicetree/bindings/net/*.

Required:

- phy-handle		: Phandle to a PHY on the MDIO bus.
			  Defined in ethernet.txt.

- phy-connection-type	: Defined in ethernet.txt.

- mdio			: "mdio" node, defined in mdio.txt.

- ethernet-phy		: "ethernet-phy" node, defined in phy.txt.

Example:

	ethernet@0,0 {
		compatible = "fsl,enetc";
		reg = <0x000000 0 0 0 0>;
		phy-handle = <&sgmii_phy0>;
		phy-connection-type = "sgmii";

		mdio {
			#address-cells = <1>;
			#size-cells = <0>;
			sgmii_phy0: ethernet-phy@2 {
				reg = <0x2>;
			};
		};
	};

2) The ENETC port is an internal port or has a fixed-link external
connection:

In this case, the ENETC port node defines a fixed link connection,
as specified by "fixed-link.txt", under
Documentation/devicetree/bindings/net/*.

Required:

- fixed-link	: "fixed-link" node, defined in "fixed-link.txt".

Example:
	ethernet@0,2 {
		compatible = "fsl,enetc";
		reg = <0x000200 0 0 0 0>;
		fixed-link {
			speed = <1000>;
			full-duplex;
		};
	};