ARM: mvebu: Add BootROM to Armada 370/XP device tree

In order to access the SoC BootROM, we need to declare a mapping
(through a ranges property). The mbus driver will use this property
to allocate a suitable address decoding window.

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Tested-by: Andrew Lunn <andrew@lunn.ch>
Tested-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>