scftorture: Avoid additional div operation.

Replace "scfp->cpu % nr_cpu_ids" with "cpu". This has been computed
earlier.

Tested-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Tested-by: Boqun Feng <boqun.feng@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

Author: Sebastian Andrzej Siewior

kernel/scftorture.c

@@ -463,7 +463,7 @@ static int scftorture_invoker(void *arg)
 
 	// Make sure that the CPU is affinitized appropriately during testing.
 	curcpu = raw_smp_processor_id();
-	WARN_ONCE(curcpu != scfp->cpu % nr_cpu_ids,
+	WARN_ONCE(curcpu != cpu,
 		  "%s: Wanted CPU %d, running on %d, nr_cpu_ids = %d\n",
 		  __func__, scfp->cpu, curcpu, nr_cpu_ids);