cpufreq: remove unnecessary check in __cpufreq_governor()

We don't need to check if event is CPUFREQ_GOV_POLICY_INIT and put
governor module as we are sure event can only be START/STOP here.

Remove the useless check.

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