rtc: Adjust failure return code for cmos_set_alarm()

When mc146818_avoid_UIP() fails to return a valid value, this is because
UIP didn't clear in the timeout period. Adjust the return code in this
case to -ETIMEDOUT.

Tested-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
Reviewed-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
Acked-by: Mateusz Jończyk <mat.jonczyk@o2.pl>
Cc:  <stable@vger.kernel.org>
Fixes: cdedc45 ("rtc: cmos: avoid UIP when reading alarm time")
Fixes: cd17420 ("rtc: cmos: avoid UIP when writing alarm time")
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Link: https://lore.kernel.org/r/20231128053653.101798-3-mario.limonciello@amd.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Author: superm1

drivers/rtc/rtc-cmos.c

@@ -292,7 +292,7 @@ static int cmos_read_alarm(struct device *dev, struct rtc_wkalrm *t)
 
 	/* This not only a rtc_op, but also called directly */
 	if (!is_valid_irq(cmos->irq))
-		return -EIO;
+		return -ETIMEDOUT;
 
 	/* Basic alarms only support hour, minute, and seconds fields.
 	 * Some also support day and month, for alarms up to a year in
@@ -557,7 +557,7 @@ static int cmos_set_alarm(struct device *dev, struct rtc_wkalrm *t)
 	 * Use mc146818_avoid_UIP() to avoid this.
 	 */
 	if (!mc146818_avoid_UIP(cmos_set_alarm_callback, &p))
-		return -EIO;
+		return -ETIMEDOUT;
 
 	cmos->alarm_expires = rtc_tm_to_time64(&t->time);