net/dsa: don't use flush_scheduled_work()

flush_scheduled_work() is deprecated and scheduled to be removed.
Directly flush dst->link_poll_work on remove instead.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NLennert Buytenhek <buytenh@wantstofly.org>

net/dsa/dsa.c

@@ -390,7 +390,7 @@ static int dsa_remove(struct platform_device *pdev)
 	if (dst->link_poll_needed)
 		del_timer_sync(&dst->link_poll_timer);
 
-	flush_scheduled_work();
+	flush_work_sync(&dst->link_poll_work);
 
 	for (i = 0; i < dst->pd->nr_chips; i++) {
 		struct dsa_switch *ds = dst->ds[i];