uboot-phytec

board/freescale:Remove use of CONFIG_SPL_NAND_MINIMAL

CONFIG_SPL_NAND_MINIMAL should not be used as it was defined for temporary
review purpose.

So, use CONFIG_SPL_NAND_BOOT config.

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