Do not set tab-width by default with basic elixir offset

Author: tonini

elixir-mode.el

@@ -509,7 +509,6 @@ just return nil."
   (set (make-local-variable 'comment-end) "")
   (set (make-local-variable 'comment-start-skip) "#+ *")
   (set (make-local-variable 'comment-use-syntax) t)
-  (set (make-local-variable 'tab-width) elixir-basic-offset)
   (set (make-local-variable 'syntax-propertize-function)
        #'elixir-syntax-propertize-function)
   (set (make-local-variable 'imenu-generic-expression)