drivers/rtc/interface.c: check the error after __rtc_read_time()

In __rtc_set_alarm(), the error after __rtc_read_time() is not checked.
If rtc device fail to read time, we cannot guarantee the following
process.

Add the verification code for returned __rtc_read_time() error.

Signed-off-by: Hyogi Gim <[e-mail]>
Acked-by: Alessandro Zummo <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/rtc/interface.c

···
 
 	/* Make sure we're not setting alarms in the past */
 	err = __rtc_read_time(rtc, &tm);
+	if (err)
+		return err;
 	rtc_tm_to_time(&tm, &now);
 	if (scheduled <= now)
 		return -ETIME;