[mle] set rx-on-when-idle when stopping Thread (#2558)

src/core/thread/mesh_forwarder.cpp

@@ -396,15 +396,6 @@ exit:
     return error;
 }
 
-void MeshForwarder::SetRxOff(void)
-{
-    ThreadNetif &netif = GetNetif();
-
-    netif.GetMac().SetRxOnWhenIdle(false);
-    mDataPollManager.StopPolling();
-    netif.GetSupervisionListener().Stop();
-}
-
 bool MeshForwarder::GetRxOnWhenIdle(void)
 {
     return GetNetif().GetMac().GetRxOnWhenIdle();

src/core/thread/mesh_forwarder.hpp

@@ -119,12 +119,6 @@ public:
      */
     void HandleResolved(const Ip6::Address &aEid, otError aError);
 
-    /**
-     * This method sets the radio receiver and polling timer off.
-     *
-     */
-    void SetRxOff(void);
-
     /**
      * This method indicates whether or not rx-on-when-idle mode is enabled.
      *

src/core/thread/mle.cpp

@@ -598,7 +598,7 @@ otError Mle::SetStateDetached(void)
     mParentRequestState = kParentIdle;
     mParentRequestTimer.Stop();
     mChildUpdateRequestTimer.Stop();
-    netif.GetMeshForwarder().SetRxOff();
+    netif.GetMeshForwarder().SetRxOnWhenIdle(true);
     netif.GetMac().SetBeaconEnabled(false);
     netif.GetMle().HandleDetachStart();
     netif.GetIp6().SetForwardingEnabled(false);