rtc: rzn1: Fix error code in probe

There is a copy and paste error so this code returns the wrong variable.

Fixes: deeb4b53 ("rtc: rzn1: Add new RTC driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/YoZMg1dmHHSJEfE9@kili