face: eliminate Transport::Packet wrapper type

Refs: #4843
Change-Id: I5977be55e8bdac33c989e3b8523fea764f304c37
diff --git a/daemon/face/multicast-udp-transport.cpp b/daemon/face/multicast-udp-transport.cpp
index 689b7e0..5017e7d 100644
--- a/daemon/face/multicast-udp-transport.cpp
+++ b/daemon/face/multicast-udp-transport.cpp
@@ -82,13 +82,13 @@
 }
 
 void
-MulticastUdpTransport::doSend(Transport::Packet&& packet)
+MulticastUdpTransport::doSend(const Block& packet, const EndpointId&)
 {
   NFD_LOG_FACE_TRACE(__func__);
 
-  m_sendSocket.async_send_to(boost::asio::buffer(packet.packet), m_multicastGroup,
-                             // packet.packet is copied into the lambda to retain the underlying Buffer
-                             [this, p = packet.packet] (auto&&... args) {
+  m_sendSocket.async_send_to(boost::asio::buffer(packet), m_multicastGroup,
+                             // 'packet' is copied into the lambda to retain the underlying Buffer
+                             [this, packet] (auto&&... args) {
                                this->handleSend(std::forward<decltype(args)>(args)...);
                              });
 }