mtd: nand: vf610_nfc: add device tree bindings

Signed-off-by: Bill Pringlemeir <bpringlemeir@nbsps.com>
Acked-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Stefan Agner <stefan@agner.ch>
[Brian: fixup #size-cells in example]
Signed-off-by: Brian Norris <computersforpeace@gmail.com>