fix NMEA Timestamp for good

src/gps/NMEAWPL.cpp

@@ -59,8 +59,10 @@ uint32_t printGGA(char *buf, size_t bufsz, const meshtastic_Position &pos)
 {
     GeoCoord geoCoord(pos.latitude_i, pos.longitude_i, pos.altitude);
     tm *t = localtime((time_t *)&pos.timestamp);
-    if (getRTCQuality() > 0) // use the device clock if we got time from somewhere. If not, use the GPS timestamp.
-        t = localtime((time_t *)getValidTime(RTCQuality::RTCQualityDevice));
+    if (getRTCQuality() > 0) { // use the device clock if we got time from somewhere. If not, use the GPS timestamp.
+        uint32_t rtc_sec = getValidTime(RTCQuality::RTCQualityDevice);
+        t = localtime((time_t *)&rtc_sec);
+    }
 
     uint32_t len = snprintf(
         buf, bufsz, "$GNGGA,%02d%02d%02d.%02d,%02d%07.4f,%c,%03d%07.4f,%c,%u,%02u,%04u,%04d,%c,%04d,%c,%d,%04d", t->tm_hour,