PXA3xx NAND DT bindings

Required properties:

 - compatible:		Should be set to one of the following:
			marvell,pxa3xx-nand
			marvell,armada370-nand
			marvell,armada-8k-nand
 - reg: 		The register base for the controller
 - interrupts:		The interrupt to map
 - #address-cells:	Set to <1> if the node includes partitions
 - marvell,system-controller: Set to retrieve the syscon node that handles
			NAND controller related registers (only required
			with marvell,armada-8k-nand compatible).

Optional properties:

 - dmas:			dma data channel, see dma.txt binding doc
 - marvell,nand-enable-arbiter:	Set to enable the bus arbiter
 - marvell,nand-keep-config:	Set to keep the NAND controller config as set
				by the bootloader
 - num-cs:			Number of chipselect lines to use
 - nand-on-flash-bbt: 		boolean to enable on flash bbt option if
				not present false
 - nand-ecc-strength:           number of bits to correct per ECC step
 - nand-ecc-step-size:          number of data bytes covered by a single ECC step

The following ECC strength and step size are currently supported:

 - nand-ecc-strength = <1>, nand-ecc-step-size = <512>
 - nand-ecc-strength = <4>, nand-ecc-step-size = <512>
 - nand-ecc-strength = <8>, nand-ecc-step-size = <512>

Example:

	nand0: nand@43100000 {
		compatible = "marvell,pxa3xx-nand";
		reg = <0x43100000 90>;
		interrupts = <45>;
		dmas = <&pdma 97 0>;
		dma-names = "data";
		#address-cells = <1>;

		marvell,nand-enable-arbiter;
		marvell,nand-keep-config;
		num-cs = <1>;

		/* partitions (optional) */
	};

