* Allwinner sun8i EMAC ethernet controller

Required properties:
- compatible: should be one of the following string:
		"allwinner,sun8i-a83t-emac"
		"allwinner,sun8i-h3-emac"
		"allwinner,sun50i-a64-emac"
- reg: address and length of the register for the device.
- syscon: A phandle to the syscon of the SoC with one of the following
 compatible string:
  - allwinner,sun8i-h3-system-controller
  - allwinner,sun8i-a64-system-controller
  - allwinner,sun8i-a83t-system-controller
- interrupts: interrupt for the device
- clocks: A phandle to the reference clock for this device
- clock-names: should be "ahb"
- resets: A phandle to the reset control for this device
- reset-names: should be "ahb"
- phy-mode: See ethernet.txt
- phy-handle: See ethernet.txt
- #address-cells: shall be 1
- #size-cells: shall be 0

Optional properties:
- allwinner,tx-delay: TX clock delay chain value. Range value is 0-0x07. Default is 0)
- allwinner,rx-delay: RX clock delay chain value. Range value is 0-0x1F. Default is 0)
Both delay properties does not have units, there are arbitrary value.
The TX/RX clock delay chain settings are board specific and could be found
in vendor FEX files.

Optional properties for "allwinner,sun8i-h3-emac":
- allwinner,leds-active-low: EPHY LEDs are active low

Required child node of emac:
- mdio bus node: should be named mdio

Required properties of the mdio node:
- #address-cells: shall be 1
- #size-cells: shall be 0

The device node referenced by "phy" or "phy-handle" should be a child node
of the mdio node. See phy.txt for the generic PHY bindings.

Required properties of the phy node with "allwinner,sun8i-h3-emac":
- clocks: an extra phandle to the reference clock for the EPHY
- resets: an extra phandle to the reset control for the EPHY

Required properties for the system controller:
- reg: address and length of the register for the device.
- compatible: should be one of the following string:
		"allwinner,sun8i-h3-system-controller"
		"allwinner,sun8i-a64-system-controller"
		"allwinner,sun8i-a83t-system-controller"

Example:

emac: ethernet@1c0b000 {
	compatible = "allwinner,sun8i-h3-emac";
	syscon = <&syscon>;
	reg = <0x01c0b000 0x104>;
	interrupts = <GIC_SPI 82 IRQ_TYPE_LEVEL_HIGH>;
	resets = <&ccu RST_BUS_EMAC>;
	reset-names = "ahb";
	clocks = <&ccu CLK_BUS_EMAC>;
	clock-names = "ahb";
	#address-cells = <1>;
	#size-cells = <0>;

	phy = <&int_mii_phy>;
	phy-mode = "mii";
	allwinner,leds-active-low;
	mdio: mdio {
		#address-cells = <1>;
		#size-cells = <0>;
		int_mii_phy: ethernet-phy@1 {
			reg = <1>;
			clocks = <&ccu CLK_BUS_EPHY>;
			resets = <&ccu RST_BUS_EPHY>;
		};
	};
};
