Staging: lustre: Fix paranthesis not required around return

This patch fixes the following checkpatch.pl warning in lustre/ldlm/ldlm_extent.c-
ERROR: return is not a function, parentheses are not required
Signed-off-by: Rashika Kheria <rashika.kheria@gmail.com>
Reviewed-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/ldlm/ldlm_extent.c

@@ -144,7 +144,7 @@ struct ldlm_interval *ldlm_interval_detach(struct ldlm_lock *l)
 	l->l_tree_node = NULL;
 	list_del_init(&l->l_sl_policy);
 
-	return (list_empty(&n->li_group) ? n : NULL);
+	return list_empty(&n->li_group) ? n : NULL;
 }
 
 static inline int lock_mode_to_index(ldlm_mode_t mode)