LwipIntfDev - disconnect()/end() should not clear static IP settings (#1866)

Author: JAndrassy

libraries/lwIP_Ethernet/src/LwipIntfDev.h

@@ -400,7 +400,7 @@ void LwipIntfDev<RawDev>::end() {
     RawDev::end();
 
     netif_remove(&_netif);
-    memset(&_netif, 0, sizeof(_netif));
+
     _started = false;
 }