poke: use unsetInterestFilter on Face instead of shutdown

refs #4642

Change-Id: I7b73c7bcde0763226a15d465046db2f4b7bb9b05
diff --git a/tools/peek/ndnpoke/ndnpoke.hpp b/tools/peek/ndnpoke/ndnpoke.hpp
index 8aa8740..f297f9d 100644
--- a/tools/peek/ndnpoke/ndnpoke.hpp
+++ b/tools/peek/ndnpoke/ndnpoke.hpp
@@ -59,9 +59,6 @@
     return m_wasDataSent;
   }
 
-public:
-  signal::Signal<NdnPoke> afterFinish;
-
 private:
   shared_ptr<Data>
   createDataPacket();
@@ -78,6 +75,7 @@
   std::istream& m_inStream;
   const PokeOptions& m_options;
 
+  const RegisteredPrefixId* m_registeredPrefix;
   bool m_wasDataSent;
 };