mvebu: add support for the Armada XP GP board (DB-MV784MP-GP)

This Armada XP GP board from Marvell comes with:

* 2GB DDR3 DIMM
* 1GB NAND flash (8-bit interface)
* 16MB NOR flash (16-bot interrface)
* 16MB SPI flash
* SDIO module
* 3 PCIe
* 1 SATA link
* 2 USB EHCI
* 1 internal SSD
* 4 Ethernet Gigabit
* 1 RS232 port over USB

Signed-off-by: Seif Mazareeb <seif.mazareeb@gmail.com>

SVN-Revision: 39568