cpufreq: stats: Refactor common code into __cpufreq_stats_create_table()

cpufreq_frequency_get_table() is called from all callers of
__cpufreq_stats_create_table(). So, move it inside.

Suggested-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Saravana Kannan <skannan@codeaurora.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>