src: drop 'virtual' from functions marked 'final' or 'override'

Change-Id: Ieb6df864ab82f77b2bee9e83aa0bfa2005715950
Refs: #3857
diff --git a/src/security/transform/base64-encode.hpp b/src/security/transform/base64-encode.hpp
index ac9c664..7e9d99d 100644
--- a/src/security/transform/base64-encode.hpp
+++ b/src/security/transform/base64-encode.hpp
@@ -46,14 +46,14 @@
   /**
    * @brief Read partial transformation result (if exists) from BIO
    */
-  virtual void
+  void
   preTransform() final;
 
   /**
-   * @brief Encode @data into base64 format.
+   * @brief Encode @p data into base64 format.
    * @return The number of input bytes that have been accepted by the converter.
    */
-  virtual size_t
+  size_t
   convert(const uint8_t* data, size_t dataLen) final;
 
   /**
@@ -61,7 +61,7 @@
    *
    * This method with read all encoding results from the converter and write them into next module.
    */
-  virtual void
+  void
   finalize() final;
 
   /**