ARM: dts: berlin: add the Marvell Armada 1500 pro

Adds initial support for the Marvell Armada 1500 pro (BG2Q) SoC (Berlin family).
The SoC has nodes for cpu, l2 cache controller, interrupt controllers, local
timer, apb timers and uarts for now. Also add corresponding binding documentation.

Signed-off-by: Antoine Tenart <antoine.tenart@free-electrons.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>