dt-bindings: net: Add DT bindings for Socionext Netsec

* Socionext NetSec Ethernet Controller IP

Required properties:

- compatible: Should be "socionext,synquacer-netsec"

- reg: Address and length of the control register area, followed by the

       address and length of the EEPROM holding the MAC address and

       microengine firmware

- interrupts: Should contain ethernet controller interrupt

- clocks: phandle to the PHY reference clock

- clock-names: Should be "phy_ref_clk"

- phy-mode: See ethernet.txt file in the same directory

- phy-handle: See ethernet.txt in the same directory.

- mdio device tree subnode: When the Netsec has a phy connected to its local

		mdio, there must be device tree subnode with the following

		required properties:

	- #address-cells: Must be <1>.

	- #size-cells: Must be <0>.

	For each phy on the mdio bus, there must be a node with the following

	fields:

	- compatible: Refer to phy.txt

	- reg: phy id used to communicate to phy.

Optional properties: (See ethernet.txt file in the same directory)

- dma-coherent: Boolean property, must only be present if memory

	accesses performed by the device are cache coherent.

- local-mac-address: See ethernet.txt in the same directory.

- mac-address: See ethernet.txt in the same directory.

- max-speed: See ethernet.txt in the same directory.

- max-frame-size: See ethernet.txt in the same directory.

Example:

	eth0: ethernet@522d0000 {

		compatible = "socionext,synquacer-netsec";

		reg = <0 0x522d0000 0x0 0x10000>, <0 0x10000000 0x0 0x10000>;

		interrupts = <GIC_SPI 176 IRQ_TYPE_LEVEL_HIGH>;

		clocks = <&clk_netsec>;

		clock-names = "phy_ref_clk";

		phy-mode = "rgmii";

		max-speed = <1000>;

		max-frame-size = <9000>;

		phy-handle = <&phy1>;

		mdio {

			#address-cells = <1>;

			#size-cells = <0>;

			phy1: ethernet-phy@1 {

				compatible = "ethernet-phy-ieee802.3-c22";

				reg = <1>;

			};

		};