powerpc/p1022ds: Add support for NAND and NAND boot using SPL

Add defines needed to access NAND, remove second flash bank that is
actually connected to NAND.

Add nand booting support for P1022DS with hardcoded DDR config using
SPL framework from 2011

Signed-off-by: Matthew McClintock <msm@freescale.com>
Signed-off-by: Jerry Huang <Chang-Ming.Huang@freescale.com>
Signed-off-by: Jiang Yutang <b14898@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Andy Fleming <afleming@freescale.com>