With the upcoming addition of the Armada 38x DDR support, which is not
compatible to the Armada XP DDR init code, we need to introduce a new
directory infrastructure. To support multiple Marvell DDR controller.

This will be the new structure:

     drivers/ddr/marvell/axp
     Supporting Armada XP (AXP) devices (and perhaps Armada 370)

     drivers/ddr/marvell/a38x
     Supporting Armada 38x devices (and perhaps Armada 39x)

Signed-off-by: Stefan Roese <sr@denx.de>