cpufreq: schedutil: Use to_gov_attr_set() to get the gov_attr_set

The to_gov_attr_set() has been moved to the cpufreq.h, so use it to get
the gov_attr_set.
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

kernel/sched/cpufreq_schedutil.c

@@ -539,7 +539,7 @@ ATTRIBUTE_GROUPS(sugov);
 
 static void sugov_tunables_free(struct kobject *kobj)
 {
-	struct gov_attr_set *attr_set = container_of(kobj, struct gov_attr_set, kobj);
+	struct gov_attr_set *attr_set = to_gov_attr_set(kobj);
 
 	kfree(to_sugov_tunables(attr_set));
 }