fix a rare GPS data corruption condition (#890)

* fix a rare GPS data corruption condition

* don't use hasLock to determine validity

src/gps/GPS.cpp

@@ -206,7 +206,7 @@ void GPS::publishUpdate()
 
         // Notify any status instances that are observing us
         const meshtastic::GPSStatus status =
-            meshtastic::GPSStatus(hasLock(), isConnected(), latitude, longitude, altitude, dop, heading, numSatellites);
+            meshtastic::GPSStatus(hasValidLocation, isConnected(), latitude, longitude, altitude, dop, heading, numSatellites);
         newStatus.notifyObservers(&status);
     }
 }

src/mesh/MeshService.cpp

@@ -209,13 +209,13 @@ NodeInfo *MeshService::refreshMyNodeInfo()
     return node;
 }
 
-int MeshService::onGPSChanged(const meshtastic::GPSStatus *unused)
+int MeshService::onGPSChanged(const meshtastic::GPSStatus *newStatus)
 {
     // Update our local node info with our position (even if we don't decide to update anyone else)
     NodeInfo *node = refreshMyNodeInfo();
     Position pos = node->position;
 
-    if (gps->hasLock()) {
+    if (newStatus->getHasLock()) {
         if (gps->altitude != 0)
             pos.altitude = gps->altitude;
         pos.latitude_i = gps->latitude;