Refactor thread_create () to call thread_get_priority in order to retrieve priority

src/threads/thread.c

@@ -264,7 +264,7 @@ thread_create (const char *name, int priority,
 
   /* Yield if the newly created thread has higher priority than the current
      thread. */
-  if (t->priority > thread_current ()->priority)
+  if (t->priority > thread_get_priority ())
     thread_yield ();
 
   return tid;