board/bsc9132qds:Add NAND boot support using new SPL format

- Add NAND boot target
   - defines constants
   - Add spl_minimal.c to initialise DDR
   - update TLB, LAW entries as per NAND boot

Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>