rtc: rtc-nuc900: fix loop timeout test

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: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

drivers/rtc/rtc-nuc900.c

@@ -93,7 +93,7 @@ static int *check_rtc_access_enable(struct nuc900_rtc *nuc900_rtc)
 	__raw_writel(AERPOWERON, nuc900_rtc->rtc_reg + REG_RTC_AER);
 
 	while (!(__raw_readl(nuc900_rtc->rtc_reg + REG_RTC_AER) & AERRWENB)
-								&& timeout--)
+								&& --timeout)
 		mdelay(1);
 
 	if (!timeout)