face: remove pointless method UdpFace::handleFirstReceive

Simply call DatagramFace::receiveDatagram directly.

Change-Id: Icec976fb9f4a008d08ece56c28ac652ea615bc76
diff --git a/daemon/face/udp-channel.cpp b/daemon/face/udp-channel.cpp
index b01d699..8d1e780 100644
--- a/daemon/face/udp-channel.cpp
+++ b/daemon/face/udp-channel.cpp
@@ -236,8 +236,8 @@
                       true);
   }
 
-  //Passing the message to the correspondent face
-  face->handleFirstReceive(m_inputBuffer, nBytesReceived, error);
+  // dispatch the datagram to the face for processing
+  face->receiveDatagram(m_inputBuffer, nBytesReceived, error);
 
   m_socket->async_receive_from(boost::asio::buffer(m_inputBuffer, MAX_NDN_PACKET_SIZE),
                                m_newRemoteEndpoint,