org-clock: Small refactoring

* lisp/org-clock.el (org-clock-in): Use
  `org-refresh-effort-properties'.

lisp/org-clock.el

@@ -1191,9 +1191,7 @@ time as the start time.  See `org-clock-continuously' to make this
 the default behavior."
   (interactive "P")
   (setq org-clock-notification-was-shown nil)
-  (org-refresh-properties
-   org-effort-property '((effort . identity)
-			 (effort-minutes . org-duration-string-to-minutes)))
+  (org-refresh-effort-properties)
   (catch 'abort
     (let ((interrupting (and (not org-clock-resolving-clocks-due-to-idleness)
 			     (org-clocking-p)))