arm: dts: Convert mvebu device tree files to 64 bits

In order to be able to use more than 4GB of RAM when the LPAE is
activated, the dts must be converted in 64 bits.

Armada XP and Armada 370 share a dtsi file which have also be
converted to 64 bits. This lead to convert all the device tree files
to 64 bits even the one used for Armada 370 (which don't support
LPAE)

This was heavily based on the work of Lior Amsalem.

Signed-off-by: Lior Amsalem <alior@marvell.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>