rtnetlink_server: Avoid refreshing for gateway changes

Instead of refreshing all of the objects, we can just update the
ethernet object that has the gateway route.

Change-Id: Ib1922273b625b1400625c6a851330e3642a8c647
Signed-off-by: William A. Kennington III <wak@google.com>
diff --git a/src/ethernet_interface.cpp b/src/ethernet_interface.cpp
index 94a8b60..c2e3e63 100644
--- a/src/ethernet_interface.cpp
+++ b/src/ethernet_interface.cpp
@@ -944,7 +944,7 @@
     EthernetInterfaceIntf::defaultGateway(gateway);
 
     writeConfigurationFile();
-    manager.reloadConfigs();
+    manager.reloadConfigsNoRefresh();
 
     return gateway;
 }
@@ -973,7 +973,7 @@
     EthernetInterfaceIntf::defaultGateway6(gateway);
 
     writeConfigurationFile();
-    manager.reloadConfigs();
+    manager.reloadConfigsNoRefresh();
 
     return gateway;
 }