* TSEC-compatible ethernet nodes

Properties:

  - compatible : Should be "fsl,etsec2" or "gianfar"
  - reg : Offset and length of the register set for the device. If this is
    missing, a subnode with a name prefix "queue-group" must be provided to
    provide the <reg> property.
  - phy-handle : See ethernet.txt file in the same directory.
  - phy-connection-type : See ethernet.txt file in the same directory. This
    property is only really needed if the connection is of type "rgmii-id",
    "rgmii-rxid" and "rgmii-txid" as all other connection types are detected
    by hardware.
  - ranges : an <empty> value if subnode "queue-group" is present, specifying
    that no address translation is required between them TSEC parent node and
    the child "queue-group" node.

Example:
	ethernet@24000 {
		compatible = "fsl,etsec2";
		reg = <0x24000 0x1000>;
		phy-handle = <&phy0>;
		phy-connection-type = "sgmii";
	};

An alternate description with "queue-group" subnode example:
	ethernet@24000 {
		compatible = "fsl,etsec2";
		phy-handle = <&phy0>;
		phy-connection-type = "sgmii";
		ranges;

		queue-group {
			reg = <0x24000 0x1000>;
		};
	};

Child nodes of the TSEC controller are typically the individual PHY devices
connected via the MDIO bus (sometimes the MDIO bus controller is separate).

* MDIO IO device

The MDIO is a bus to which the PHY devices are connected.  For each
device that exists on this bus, a PHY node should be created.

Required properties:
  - compatible : Should define the compatible device type for the
    mdio. Currently supported string/device is "fsl,etsec2-mdio".
  - reg : Offset and length of the register set for the device

Example:

	mdio@24520 {
		compatible = "fsl,etsec2-mdio";
		reg = <0x24520 0x20>;

		ethernet-phy@0 {
			reg = <0>;
		};
	};

* TBI Internal MDIO bus

As of this writing, every tsec is associated with an internal TBI PHY.
This PHY is accessed through the local MDIO bus.  These buses are defined
similarly to the mdio buses.  The TBI PHYs underneath them are similar to
normal PHYs, but the reg property is considered instructive, rather than
descriptive.  The reg property should be chosen so it doesn't interfere
with other PHYs on the bus.  The TBI PHYs are referred to by a "tbi-handle"
property under the tsec node, which has a similar meaning of "phy-handle".

Example:
	ethernet@24000 {
		phy-handle = <&tbi1>;
	};

	mdio@24520 {
		tbi1: tbi-phy@1f {
			reg = <0x1f>;
		};
	};
