mtd: rawnand: arasan: Add new Arasan NAND controller

Add the Arasan NAND controller driver. This brings only NAND
controller support. The ECC engine being a bit subtle, hardware ECC
support will be added in a second time.

This work is based on contributions from Naga Sureshkumar Relli.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://lore.kernel.org/linux-mtd/20200519074549.23673-8-miquel.raynal@bootlin.com