cpufreq: Don't pass CPU to cpufreq_add_dev_{symlink|interface}()

Pointer to struct cpufreq_policy is already passed to these routines
and we don't need to send policy->cpu to them as well.  So, get rid
of this extra argument and use policy->cpu everywhere.

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