vdo: omit need_resched() before cond_resched()

There's no need to call need_resched() because cond_resched() will do
nothing if need_resched() returns false.

Reviewed-by: Matthew Sakai <msakai@redhat.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

drivers/md/dm-vdo/funnel-workqueue.c

@@ -252,8 +252,7 @@ static void service_work_queue(struct simple_work_queue *queue)
 		 * This speeds up some performance tests; that "other work" might include other VDO
 		 * threads.
 		 */
-		if (need_resched())
-			cond_resched();
+		cond_resched();
 	}
 
 	run_finish_hook(queue);