daemon: mark some classes and methods 'final'

As suggested by gcc's -Wsuggest-final-types and -Wsuggest-final-methods

Change-Id: I1622857ee53581efd0c6ce3fe93199c72202d817
diff --git a/daemon/face/ethernet-factory.hpp b/daemon/face/ethernet-factory.hpp
index 9b25b3c..578a901 100644
--- a/daemon/face/ethernet-factory.hpp
+++ b/daemon/face/ethernet-factory.hpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
 /*
- * Copyright (c) 2014-2018,  Regents of the University of California,
+ * Copyright (c) 2014-2021,  Regents of the University of California,
  *                           Arizona Board of Regents,
  *                           Colorado State University,
  *                           University Pierre & Marie Curie, Sorbonne University,
@@ -34,7 +34,7 @@
 
 /** \brief Protocol factory for Ethernet
  */
-class EthernetFactory : public ProtocolFactory
+class EthernetFactory final : public ProtocolFactory
 {
 public:
   static const std::string&
@@ -77,15 +77,15 @@
    */
   void
   doProcessConfig(OptionalConfigSection configSection,
-                  FaceSystem::ConfigContext& context) override;
+                  FaceSystem::ConfigContext& context) final;
 
   void
   doCreateFace(const CreateFaceRequest& req,
                const FaceCreatedCallback& onCreated,
-               const FaceCreationFailedCallback& onFailure) override;
+               const FaceCreationFailedCallback& onFailure) final;
 
   std::vector<shared_ptr<const Channel>>
-  doGetChannels() const override;
+  doGetChannels() const final;
 
   /** \brief Create EthernetChannel on \p netif if requested by \p m_unicastConfig.
    *  \return new or existing channel, or nullptr if no channel should be created