sched/fair: Do not use check_for_migration() while using CASS

WALT has check_for_migration() that calls find_energy_efficient_cpu().
But with CASS, using find_energy_efficient_cpu() is irrelevant. Since
check_for_migration() also doesn't prove to be much useful even without
the reference to find_energy_efficient_cpu(), do not use it while using
CASS with WALT. There's no need to use IS_ENABLED() for CONFIG_SCHED_WALT
here since the function is already guarded with CONFIG_SCHED_WALT.

Signed-off-by: Tashfin Shakeer Rhythm <tashfinshakeerrhythm@gmail.com>

kernel/sched/fair.c

@@ -13135,6 +13135,9 @@ void check_for_migration(struct rq *rq, struct task_struct *p)
 	int prev_cpu = task_cpu(p);
 	struct sched_domain *sd = NULL;
 
+	if (IS_ENABLED(CONFIG_SCHED_CASS))
+		return;
+
 	if (rq->misfit_task_load) {
 		if (rq->curr->state != TASK_RUNNING ||
 		    rq->curr->nr_cpus_allowed == 1)