uboot-imx

configs: Make NAND_BOOT and ONENAND_BOOT imply NAND

Some boards indicate support from booting NAND or
ONENAND booting, but don't enable the CONFIG_NAND.  This
makes those boards imply NAND which will make
enabling other flags that are dependent on CONFIG_NAND
possible and easier to migrate.

Signed-off-by: Adam Ford <aford173@gmail.com>