mtd: atmel_nand: add MODULE_DEVICE_TABLE for nfc driver

This patch also add a const keyword for the of_device_id of nfc.

Signed-off-by: Josh Wu <josh.wu@atmel.com>
Acked-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>