ARM: dts: add support for Laird SOM60 module and DVK boards

This adds support for Lairds upcoming SOM module, featuring Marvell WiFi
and Bluetooth, 2Gb NAND / 1Gb LPDDR SDRAM, and an Atmel SAMA5D3 CPU.

Signed-off-by: Ben Whitten <ben.whitten@lairdtech.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>