mtd: nand: xway: Avoid messing up with IO_ADDR_W in ->cmd_ctrl()

The ->cmd_ctrl() function is adjusting the ->IO_ADDR_W value depending
on the command type each time NAND_CTRL_CHANGE is passed. This is not
only useless but can lead to an ->IO_ADDR_W corruption.

Get rid of this logic and rely on the NAND_CLE and NAND_ALE flags to
deduce the iomem address to write the cmd argument to.

Signed-off-by: John Crispin <john@phrozen.org>
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>