mtd: rawnand: txx9ndfmc: Switch to module_platform_driver()

While module_platform_driver_probe() offers the possibility to discard
.probe() and .remove() in some situations, the handling is difficult and
in today's systems the few hundred bytes that can be saved have little
importance. So convert the driver to be a normal driver that can be
bound and unbound at runtime as most other drivers, too.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20231102220246.3336154-8-u.kleine-koenig@pengutronix.de