if gpssmm cant be opened, return prematurely

linux/devices/GPSHyperionLinuxController.cpp

@@ -112,6 +112,7 @@ void GPSHyperionLinuxController::readGpsDataFromGpsd() {
 #if FSFW_VERBOSE_LEVEL >= 1
     sif::warning << "GPSHyperionHandler::readGpsDataFromGpsd: Opening GPSMM failed" << std::endl;
 #endif
+    return;
   }
   gps_data_t *gps = nullptr;
   gps = myGpsmm.read();