wait_for_completion_timeout() and readl_poll_timeout() don't handle their
return value the same way.

wait_for_completion_timeout() returns 0 on time out (and >0 in all other
cases)
readl_poll_timeout() returns 0 on success and -ETIMEDOUT upon a timeout.

In order for the error handling path to work in both cases, the logic
against wait_for_completion_timeout() needs to be inverted.

Fixes: 48e6633a ("mtd: nand: mxic-ecc: Add Macronix external ECC engine support")
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/beddbc374557e44ceec897e68c4a5d12764ddbb9.1676459308.git.christophe.jaillet@wanadoo.fr