ARM: dts: mvebu: Add device tree for ATL-x530 Board

Add device tree file for x530 board. This has an Armada 385 SoC. Has
NAND-flash for user storage and SPI for booting. Covers majority of x530
and GS980MX variants.

Signed-off-by: Aryan Srivastava <aryan.srivastava@alliedtelesis.co.nz>
Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>