[ARM] Kirkwood: Add support for 88f6282

The 6282 SoC is compatible to 6280 and features faster CPU, DDR3, additional
PCIe interface, and LCD controller. More information can be found here:
http://www.marvell.com/products/processors/embedded/armada_300/armada_310.pdf



Signed-off-by: Saeed Bishara <saeed@marvell.com>
Signed-off-by: Nicolas Pitre <nico@fluxnic.net>