cpufreq: Don't create empty /sys/devices/system/cpu/cpufreq directory

When we don't have any file in cpu/cpufreq directory we shouldn't
create it. Specially with the introduction of per-policy governor
instance patchset, even governors are moved to
cpu/cpu*/cpufreq/governor-name directory and so this directory is
just not required.

Lets have it only when required.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/cpufreq_governor.c

@@ -231,6 +231,9 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 			return rc;
 		}
 
+		if (!have_governor_per_policy())
+			WARN_ON(cpufreq_get_global_kobject());
+
 		rc = sysfs_create_group(get_governor_parent_kobj(policy),
 				get_sysfs_attr(dbs_data));
 		if (rc) {
@@ -269,6 +272,9 @@ int cpufreq_governor_dbs(struct cpufreq_policy *policy,
 			sysfs_remove_group(get_governor_parent_kobj(policy),
 					get_sysfs_attr(dbs_data));
 
+			if (!have_governor_per_policy())
+				cpufreq_put_global_kobject();
+
 			if ((dbs_data->cdata->governor == GOV_CONSERVATIVE) &&
 				(policy->governor->initialized == 1)) {
 				struct cs_ops *cs_ops = dbs_data->cdata->gov_ops;