cpufreq: initialize policy rwsem before sysfs publication

In the Linux kernel, the following vulnerability has been resolved: cpufreq: initialize policy rwsem before sysfs publication cpufreq_policy_alloc() initializes policy->rwsem after kobject_init_and_add() has created the policy sysfs directory and its default attributes. A sysfs access can therefore reach a policy callback before the semaphore has been initialized. Initialize policy->rwsem before publishing the policy kobject so sysfs callbacks always see an initialized semaphore.