encoding: remove duplicate buf() and get() methods from Buffer class

Change-Id: If885d4199d6c9df9b9b46664c3641c9a14a77eab
diff --git a/src/security/transform/buffer-source.cpp b/src/security/transform/buffer-source.cpp
index b47e855..3f45c85 100644
--- a/src/security/transform/buffer-source.cpp
+++ b/src/security/transform/buffer-source.cpp
@@ -1,6 +1,6 @@
 /* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
-/**
- * Copyright (c) 2013-2016 Regents of the University of California.
+/*
+ * Copyright (c) 2013-2017 Regents of the University of California.
  *
  * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
  *
@@ -38,7 +38,7 @@
 }
 
 BufferSource::BufferSource(const Buffer& buffer)
-  : m_buf(buffer.buf())
+  : m_buf(buffer.data())
   , m_size(buffer.size())
 {
 }