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/ds1374.c b/drivers/rtc/ds1374.c
index e773dd9..f6bb296 100644
--- a/drivers/rtc/ds1374.c
+++ b/drivers/rtc/ds1374.c
@@ -107,8 +107,8 @@
 /*
  * Get the current time from the RTC
  */
-void rtc_get (struct rtc_time *tm){
-
+int rtc_get (struct rtc_time *tm){
+	int rel = 0;
 	unsigned long time1, time2;
 	unsigned int limit;
 	unsigned char tmp;
@@ -138,18 +138,23 @@
 
 	if (time1 != time2) {
 		printf("can't get consistent time from rtc chip\n");
+		rel = -1;
 	}
 
 	DEBUGR ("Get RTC s since 1.1.1970: %d\n", time1);
 
 	to_tm(time1, tm); /* To Gregorian Date */
 
-	if (rtc_read(RTC_SR_ADDR) & RTC_SR_BIT_OSF)
+	if (rtc_read(RTC_SR_ADDR) & RTC_SR_BIT_OSF) {
 		printf ("### Warning: RTC oscillator has stopped\n");
+		rel = -1;
+	}
 
 	DEBUGR ("Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
 		tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_wday,
 		tm->tm_hour, tm->tm_min, tm->tm_sec);
+
+	return rel;
 }
 
 /*