PM / OPP: Set cpu_dev->id in cpumask first

Set cpu_dev->id in cpumask first when setting up cpumask for CPUs that
share the same OPP table. This might be helpful when handling cpumask
without the original CPU bitfield set.

Signed-off-by: Pi-Cheng Chen <pi-cheng.chen@linaro.org>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>