rtc: sysfs: check features instead of ops

Test RTC_FEATURE_ALARM instead of relying on .set_alarm to know whether
alarms are available.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20210429214403.2610952-1-alexandre.belloni@bootlin.com

drivers/rtc/sysfs.c

@@ -273,7 +273,7 @@ static bool rtc_does_wakealarm(struct rtc_device *rtc)
 	if (!device_can_wakeup(rtc->dev.parent))
 		return false;
 
-	return rtc->ops->set_alarm != NULL;
+	return !!test_bit(RTC_FEATURE_ALARM, rtc->features);
 }
 
 static umode_t rtc_attr_is_visible(struct kobject *kobj,