mtd: rawnand: meson: Fix typo in function name

There is a reason why sometime we write "NAND chip" with an 's'. It
usually means several chips can be managed by the same controller. So
when initializing a single chip at a time, the wording "chip" must be
used, otherwise when talking about all the chips managed by the
controller, we want to use "chips". Fix the function name to clarify the
meson_nfc_nand_chip*s*_cleanup() helper intend.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Link: https://lore.kernel.org/linux-mtd/20240826153158.67334-1-miquel.raynal@bootlin.com