uboot-phytec

dfu: add dependency on the raw NAND core

CONFIG_DFU_NAND needs the raw NAND core being compiled.

Also fix the colibri_vf defconfig to reflect this dependency.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>