mtd: rawnand: meson: Drop cleaning platform data in .remove()

The driver core cares for unsetting platform data (see
device_unbind_cleanup()) on remove.

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/20220603210758.148493-13-u.kleine-koenig@pengutronix.de