[ACPI] Always set P-state on initialization

Otherwise a platform that supports ACPI based cpufreq
and boots up at lowest possible speed could stay there
forever.  This because the governor may request max speed,
but the code doesn't update if there is no change in
speed, and it assumed the initial state of max speed.

http://bugzilla.kernel.org/show_bug.cgi?id=4634

Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>