* Cadence MACB/GEM Ethernet controller

Required properties:
- compatible: Should be "cdns,[<chip>-]{macb|gem}"
  Use "cdns,at91rm9200-emac" Atmel at91rm9200 SoC.
  Use "cdns,at91sam9260-macb" for Atmel at91sam9 SoCs.
  Use "cdns,sam9x60-macb" for Microchip sam9x60 SoC.
  Use "cdns,np4-macb" for NP4 SoC devices.
  Use "cdns,at32ap7000-macb" for other 10/100 usage or use the generic form: "cdns,macb".
  Use "atmel,sama5d2-gem" for the GEM IP (10/100) available on Atmel sama5d2 SoCs.
  Use "atmel,sama5d29-gem" for GEM XL IP (10/100) available on Atmel sama5d29 SoCs.
  Use "atmel,sama5d3-macb" for the 10/100Mbit IP available on Atmel sama5d3 SoCs.
  Use "atmel,sama5d3-gem" for the Gigabit IP available on Atmel sama5d3 SoCs.
  Use "atmel,sama5d4-gem" for the GEM IP (10/100) available on Atmel sama5d4 SoCs.
  Use "cdns,zynq-gem" Xilinx Zynq-7xxx SoC.
  Use "cdns,zynqmp-gem" for Zynq Ultrascale+ MPSoC.
  Use "sifive,fu540-c000-gem" for SiFive FU540-C000 SoC.
  Use "microchip,sama7g5-emac" for Microchip SAMA7G5 ethernet interface.
  Use "microchip,sama7g5-gem" for Microchip SAMA7G5 gigabit ethernet interface.
  Or the generic form: "cdns,emac".
- reg: Address and length of the register set for the device
	For "sifive,fu540-c000-gem", second range is required to specify the
	address and length of the registers for GEMGXL Management block.
- interrupts: Should contain macb interrupt
- phy-mode: See ethernet.txt file in the same directory.
- clock-names: Tuple listing input clock names.
	Required elements: 'pclk', 'hclk'
	Optional elements: 'tx_clk'
	Optional elements: 'rx_clk' applies to cdns,zynqmp-gem
	Optional elements: 'tsu_clk'
- clocks: Phandles to input clocks.

Optional properties:
- mdio: node containing PHY children. If this node is not present, then PHYs
        will be direct children.

The MAC address will be determined using the optional properties
defined in ethernet.txt.

Optional properties for PHY child node:
- reset-gpios : Should specify the gpio for phy reset
- magic-packet : If present, indicates that the hardware supports waking
  up via magic packet.
- phy-handle : see ethernet.txt file in the same directory

Examples:

	macb0: ethernet@fffc4000 {
		compatible = "cdns,at32ap7000-macb";
		reg = <0xfffc4000 0x4000>;
		interrupts = <21>;
		phy-mode = "rmii";
		local-mac-address = [3a 0e 03 04 05 06];
		clock-names = "pclk", "hclk", "tx_clk";
		clocks = <&clkc 30>, <&clkc 30>, <&clkc 13>;
		ethernet-phy@1 {
			reg = <0x1>;
			reset-gpios = <&pioE 6 1>;
		};
	};