thermal: cpu_cooling: OPPs are registered for all CPUs

The OPPs are registered for all CPUs of a cpufreq policy now and we
don't need to run the loop in build_dyn_power_table(). Just check for
the policy->cpu and we should be fine.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Lukasz Luba <lukasz.luba@arm.com>
Tested-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>