ARM: dts: vf-colibri: enable NAND flash controller

Enable NAND access by adding pinmux and NAND flash controller node
to device tree. The NAND chips currently used on the Colibri VF61
requires 8-bit ECC per 512 byte page, hence specify 32-bit ECC
strength per 2k page size.

Reviewed-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Stefan Agner <stefan@agner.ch>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>