ARM: imx: reorganize nand registration to use a struct

Addiontionally make the interrupt #defines match the base address
defines MX.._NFC_BASE_ADDR.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>