LWMON5: POST RTC fix

Modify the RTC API to provide one a status for the time reported by
the rtc_get() function:
  0 - a reliable time is guaranteed,
< 0 - a reliable time isn't guaranteed (power fault, clock issues,
      and so on).

The RTC chip drivers are responsible for providing this info if the
corresponding chip supports such functionality. If not - always
report that the time is reliable.

The POST RTC test was modified to detect the RTC faults utilizing
this new rtc_get() feature.

Signed-off-by: Yuri Tikhonov <yur@emcraft.com>
diff --git a/drivers/rtc/m41t62.c b/drivers/rtc/m41t62.c
index 2bdca3b..cf2a957 100644
--- a/drivers/rtc/m41t62.c
+++ b/drivers/rtc/m41t62.c
@@ -64,7 +64,7 @@
 #define M41T62_FEATURE_HT	(1 << 0)
 #define M41T62_FEATURE_BL	(1 << 1)
 
-void rtc_get(struct rtc_time *tm)
+int rtc_get(struct rtc_time *tm)
 {
 	u8 buf[M41T62_DATETIME_REG_SIZE];
 
@@ -92,6 +92,8 @@
 	      __FUNCTION__,
 	      tm->tm_sec, tm->tm_min, tm->tm_hour,
 	      tm->tm_mday, tm->tm_mon, tm->tm_year, tm->tm_wday);
+
+	return 0;
 }
 
 void rtc_set(struct rtc_time *tm)