mtd: rawnand: meson: Fix a potential double free issue

When meson_nfc_nand_chip_cleanup() is called, it will call:
	meson_nfc_free_buffer(&meson_chip->nand);
	nand_cleanup(&meson_chip->nand);

nand_cleanup() in turn will call nand_detach() which calls the
.detach_chip() which is here meson_nand_detach_chip().

meson_nand_detach_chip() already calls meson_nfc_free_buffer(), so we
could double free some memory.

Fix it by removing the unneeded explicit call to meson_nfc_free_buffer().

Fixes: 8fae856c

 ("mtd: rawnand: meson: add support for Amlogic NAND flash controller")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Liang Yang <liang.yang@amlogic.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/ec15c358b8063f7c50ff4cd628cf0d2e14e43f49.1653064877.git.christophe.jaillet@wanadoo.fr