devm_kcalloc() returns NULL, it never returns error pointers. In the
current code we would return PTR_ERR(NULL) which is success, instead of
returning the -ENOMEM error code.
Fixes: a0a1a1ba3032 ("rtc: sysfs: facilitate attribute add to rtc device") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>