We should change this post-op to a pre-op because we want the loop to
exit with "timeout" set to zero.

Fixes: 0a89b553 ("nuc900/rtc: change the waiting for device ready implement")
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NAlexandre Belloni <alexandre.belloni@free-electrons.com>