Inline the lone add_master_key_file_silently use.

railties/lib/rails/generators/rails/master_key/master_key_generator.rb

@@ -20,17 +20,13 @@ def add_master_key_file
           say "If you lose the key, no one, including you, can access anything encrypted with it."
 
           say ""
-          add_master_key_file_silently key
+          create_file MASTER_KEY_PATH, key
           say ""
 
           ignore_master_key_file
         end
       end
 
-      def add_master_key_file_silently(key = nil)
-        create_file MASTER_KEY_PATH, key || ActiveSupport::EncryptedFile.generate_key
-      end
-
       private
         def ignore_master_key_file
           if File.exist?(".gitignore")