cpufreq: Use locking guard and __free() in cpufreq_update_policy()

Instead of using cpufreq_cpu_acquire() and cpufreq_cpu_release() in
cpufreq_update_policy(), which is the last user of these functions,
make it use __free() for policy reference counting cleanup and the
"write" locking guard for policy locking.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Acked-by: Sudeep Holla <sudeep.holla@arm.com>
Tested-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://patch.msgid.link/22654186.EfDdHjke4D@rjwysocki.net