cpufreq/cpufreq_governor: Replace synchronize_sched() with synchronize_rcu()

Now that synchronize_rcu() waits for preempt-disable regions of code
as well as RCU read-side critical sections, synchronize_sched() can be
replaced by synchronize_rcu().  This commit therefore makes this change.
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

drivers/cpufreq/cpufreq_governor.c

@@ -346,7 +346,7 @@ static inline void gov_clear_update_util(struct cpufreq_policy *policy)
 	for_each_cpu(i, policy->cpus)
 		cpufreq_remove_update_util_hook(i);
 
-	synchronize_sched();
+	synchronize_rcu();
 }
 
 static struct policy_dbs_info *alloc_policy_dbs_info(struct cpufreq_policy *policy,