face: remove nfd::ProtocolFactory type alias

Change-Id: Iac0af82a5301245e621a39f3bfc98aaed8dbaa45
diff --git a/daemon/face/protocol-factory.hpp b/daemon/face/protocol-factory.hpp
index 4535d3f..b8bba3d 100644
--- a/daemon/face/protocol-factory.hpp
+++ b/daemon/face/protocol-factory.hpp
@@ -28,6 +28,7 @@
 
 #include "channel.hpp"
 #include "face-system.hpp"
+
 #include <ndn-cxx/encoding/nfd-constants.hpp>
 #include <boost/range/adaptor/map.hpp>
 #include <boost/range/algorithm/copy.hpp>
@@ -159,9 +160,6 @@
 };
 
 } // namespace face
-
-using face::ProtocolFactory;
-
 } // namespace nfd
 
 /** \brief registers a protocol factory