mtd: rawnand: Compare the actual timing values

Avoid relying just on the default timing mode to discriminate if the
data interface must be restored. This field should only be used
at initialization time by legacy chips statically defined. Do a
memcmp() instead.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Link: https://lore.kernel.org/linux-mtd/20200529111322.7184-8-miquel.raynal@bootlin.com