Merge "Memory leak due to no stop for IpNeighborMonitor."

Tethering/src/android/net/ip/IpServer.java

@@ -1321,6 +1321,7 @@ public class IpServer extends StateMachine {
     class UnavailableState extends State {
         @Override
         public void enter() {
+            mIpNeighborMonitor.stop();
             mLastError = TetheringManager.TETHER_ERROR_NO_ERROR;
             sendInterfaceState(STATE_UNAVAILABLE);
         }