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

Change-Id: If885d4199d6c9df9b9b46664c3641c9a14a77eab
diff --git a/src/util/sha256.cpp b/src/util/sha256.cpp
index 7aeea64..034d12e 100644
--- a/src/util/sha256.cpp
+++ b/src/util/sha256.cpp
@@ -82,14 +82,14 @@
   }
 
   // constant-time buffer comparison to mitigate timing attacks
-  return CRYPTO_memcmp(lhs.get(), rhs.get(), lhs.size()) == 0;
+  return CRYPTO_memcmp(lhs.data(), rhs.data(), lhs.size()) == 0;
 }
 
 Sha256&
 Sha256::operator<<(Sha256& src)
 {
   auto buf = src.computeDigest();
-  update(buf->get(), buf->size());
+  update(buf->data(), buf->size());
   return *this;
 }