rtc: interface: Add RTC offset to alarm after fix-up

`rtc_add_offset()` is called by `__rtc_read_time()`
and `__rtc_read_alarm()` to add the RTC's offset to
the raw read-outs from the device drivers. However,
in the latter case, a fix-up algorithm is run if
the RTC device does not report a full `struct rtc_time`
alarm value. In that case, the offset was forgot to be
added.

Fixes: fd6792b ("rtc: fix alarm read and set offset")

Signed-off-by: Csókás, Bence <csokas.bence@prolan.hu>
Link: https://lore.kernel.org/r/20240619140451.2800578-1-csokas.bence@prolan.hu
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Author: Csókás, Bence

drivers/rtc/interface.c

@@ -274,10 +274,9 @@ int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 			return err;
 
 		/* full-function RTCs won't have such missing fields */
-		if (rtc_valid_tm(&alarm->time) == 0) {
-			rtc_add_offset(rtc, &alarm->time);
-			return 0;
-		}
+		err = rtc_valid_tm(&alarm->time);
+		if (!err)
+			goto done;
 
 		/* get the "after" timestamp, to detect wrapped fields */
 		err = rtc_read_time(rtc, &now);
@@ -379,6 +378,8 @@ int __rtc_read_alarm(struct rtc_device *rtc, struct rtc_wkalrm *alarm)
 	if (err && alarm->enabled)
 		dev_warn(&rtc->dev, "invalid alarm value: %ptR\n",
 			 &alarm->time);
+	else
+		rtc_add_offset(rtc, &alarm->time);
 
 	return err;
 }