Marvell MV88F6281GTW_GE Board support

This is Marvell's 88F6281_A0 based custom board developed
for wireless access point product

This patch is tested for-
1. Boot from DRAM/SPI flash/NFS
2. File transfer using tftp and loadb
3. SPI flash read/write/erase
4. Booting Linux kernel and RFS from SPI flash
5. Boot from USB supported

Reviewed-by: Ronen Shitrit <rshitrit@marvell.com>
Signed-off-by: Prafulla Wadaskar <prafulla@marvell.com>