NVIDIA Tegra NAND Flash controller

Required properties:
- compatible: Must be one of:
  - "nvidia,tegra20-nand"
- reg: MMIO address range
- interrupts: interrupt output of the NFC controller
- clocks: Must contain an entry for each entry in clock-names.
  See ../clocks/clock-bindings.txt for details.
- clock-names: Must include the following entries:
  - nand
- resets: Must contain an entry for each entry in reset-names.
  See ../reset/reset.txt for details.
- reset-names: Must include the following entries:
  - nand

Optional children nodes:
Individual NAND chips are children of the NAND controller node. Currently
only one NAND chip supported.

Required children node properties:
- reg: An integer ranging from 1 to 6 representing the CS line to use.

Optional children node properties:
- nand-ecc-mode: String, operation mode of the NAND ecc mode. Currently only
		 "hw" is supported.
- nand-ecc-algo: string, algorithm of NAND ECC.
		 Supported values with "hw" ECC mode are: "rs", "bch".
- nand-bus-width : See nand-controller.yaml
- nand-on-flash-bbt: See nand-controller.yaml
- nand-ecc-strength: integer representing the number of bits to correct
		     per ECC step (always 512). Supported strength using HW ECC
		     modes are:
		     - RS: 4, 6, 8
		     - BCH: 4, 8, 14, 16
- nand-ecc-maximize: See nand-controller.yaml
- nand-is-boot-medium: Makes sure only ECC strengths supported by the boot ROM
		       are chosen.
- wp-gpios: GPIO specifier for the write protect pin.

Optional child node of NAND chip nodes:
Partitions: see mtd.yaml

  Example:
	nand-controller@70008000 {
		compatible = "nvidia,tegra20-nand";
		reg = <0x70008000 0x100>;
		interrupts = <GIC_SPI 24 IRQ_TYPE_LEVEL_HIGH>;
		clocks = <&tegra_car TEGRA20_CLK_NDFLASH>;
		clock-names = "nand";
		resets = <&tegra_car 13>;
		reset-names = "nand";

		nand@0 {
			reg = <0>;
			#address-cells = <1>;
			#size-cells = <1>;
			nand-bus-width = <8>;
			nand-on-flash-bbt;
			nand-ecc-algo = "bch";
			nand-ecc-strength = <8>;
			wp-gpios = <&gpio TEGRA_GPIO(S, 0) GPIO_ACTIVE_LOW>;
		};
	};