Pantheon: Add Board Support for Marvell dkb board

DKB is a Development Board for PANTHEON TD/TTC(pxa920/pxa910) with
* Processor upto 806Mhz
* LPDDR1/2
* x8/x16 SLC/MLC NAND
* Footprints for eMMC & MMC x8 card

With Peripherals:
* Parallel LCD I/F
* Audio codecs (88PM8607)
* MIPI CSI-2 camera
* Marvell 88W8787 802.11n/BT module
* Marvell 2G/3G RF
* Dual analog mics & speakers, headset jack, LED, ambient
* USB2.0 HS host, OTG (mini AB)
* GPIO, GPIO expander with DIP switches for easier selection
* UART serial over USB, CIR

This patch adds basic board support with DRAM and UART functionality

Signed-off-by: Lei Wen <leiwen@marvell.com>
Signed-off-by: Prafulla Wadaskar <prafulla@marvell.com>