cpufreq: Relocate handle_update() to kill its declaration

handle_update() is declared at the top of the file as its user appear
before its definition. Relocate the routine to get rid of this.

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