dt-bindings: ARM: Document SAMA5D2-ICP

Document device tree binding for SAMA5D2 Industrial Connectivity
Platform(ICP).

Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
[cristian.birsan@microchip.com update board name to match silkscreen]
Signed-off-by: Cristian Birsan <cristian.birsan@microchip.com>
Link: https://lore.kernel.org/r/20200410164320.7658-2-cristian.birsan@microchip.com


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>