ncp: Remove unused mSendMessage from Ncp class. (#167)

src/ncp/ncp.cpp

@@ -148,12 +148,6 @@ void Ncp::SendDoneTask(void)
 {
     mSending = false;
 
-    if (mSendMessage)
-    {
-        Message::Free(*mSendMessage);
-        mSendMessage = NULL;
-    }
-
     super_t::HandleSendDone();
 }
 

src/ncp/ncp.hpp

@@ -65,7 +65,6 @@ private:
     uint8_t mSendFrame[1500];
     uint8_t mReceiveFrame[1500];
     uint8_t *mSendFrameIter;
-    Message *mSendMessage;
 };
 
 }  // namespace Thread