rtc: allow rtc_set to return an error and use it in cmd_date

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/drivers/rtc/x1205.c b/drivers/rtc/x1205.c
index 7025cf4..7a3b514 100644
--- a/drivers/rtc/x1205.c
+++ b/drivers/rtc/x1205.c
@@ -134,7 +134,7 @@
 	return 0;
 }
 
-void rtc_set(struct rtc_time *tm)
+int rtc_set(struct rtc_time *tm)
 {
 	int i;
 	u8 buf[8];
@@ -168,6 +168,8 @@
 		rtc_write(X1205_CCR_BASE + i, buf[i]);
 
 	rtc_write(X1205_REG_SR, 0);
+
+	return 0;
 }
 
 void rtc_reset(void)