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

Change-Id: If885d4199d6c9df9b9b46664c3641c9a14a77eab
diff --git a/tests/unit-tests/security/v2/validator.t.cpp b/tests/unit-tests/security/v2/validator.t.cpp
index 9945ef9..ac5ca86 100644
--- a/tests/unit-tests/security/v2/validator.t.cpp
+++ b/tests/unit-tests/security/v2/validator.t.cpp
@@ -275,7 +275,7 @@
     certificate.setFreshnessPeriod(time::hours(1));
 
     // set content
-    certificate.setContent(requestedKey.getPublicKey().buf(), requestedKey.getPublicKey().size());
+    certificate.setContent(requestedKey.getPublicKey().data(), requestedKey.getPublicKey().size());
 
     // set signature-info
     SignatureInfo info;