face: eliminate Transport::Packet wrapper type

Refs: #4843
Change-Id: I5977be55e8bdac33c989e3b8523fea764f304c37
diff --git a/daemon/face/face-endpoint.hpp b/daemon/face/face-endpoint.hpp
index cf2c466..4d33634 100644
--- a/daemon/face/face-endpoint.hpp
+++ b/daemon/face/face-endpoint.hpp
@@ -30,7 +30,8 @@
 
 namespace nfd {
 
-/** \brief Represents a face-endpoint pair in the forwarder
+/** \brief Represents a face-endpoint pair in the forwarder.
+ *  \sa face::Face, face::EndpointId
  */
 class FaceEndpoint
 {
@@ -49,7 +50,7 @@
 inline std::ostream&
 operator<<(std::ostream& os, const FaceEndpoint& fe)
 {
-  return os << "(" << fe.face.getId() << "," << fe.endpoint << ")";
+  return os << '(' << fe.face.getId() << ',' << fe.endpoint << ')';
 }
 
 } // namespace nfd