Use generic cpufreq_generic_init() routine instead of replicating the same code
here.

Cc: Mikael Starvik <starvik@axis.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>