intel_pstate: respect cpufreq policy request

When thermal or other subsystem requests to change the policy,
use that irrepective of whether cpufreq policy is PERFORMANCE or
not. Without this change, when thermal subsystem passive policy wants
to reduce performance, it still runs at 100%.

Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Signed-off-by: Kristen Carlson Accardi <kristen@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>