ACPI / CPPC: Use h/w reduced version of the PCCT structure

CPPC is enabled only on platforms which support the h/w reduced
ACPI specification, so use the h/w reduced version of the PCCT
consistently when deferencing PCCT contents.

Fixes: 337aadff

 (ACPI: Introduce CPU performance controls using CPPC)
Signed-off-by: Ashwin Chaugule <ashwin.chaugule@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>