NAND: Add support for MPC8572DS board

This patch defines 1M TLB&LAW size for NAND on MPC8572DS, assigns
0xffa00000 for CONFIG_SYS_NAND_BASE and adds other NAND supports in
config file.

It also moves environment(CONFIG_ENV_ADDR) outside of u-boot image, to
make room for the increased code size with NAND enabled.

Signed-off-by: Jason Jin <Jason.Jin@freescale.com>
Signed-off-by: Haiying Wang <Haiying.Wang@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>