cpufreq: remove useless INIT_LIST_HEAD()

list cpu_data_list has been inited staticly through LIST_HEAD,
so there's no need to call another INIT_LIST_HEAD. Simply remove
it from cppc_cpufreq_init.

Signed-off-by: Han Wang <zjuwanghan@outlook.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>