[ACPI] fix passive cooling regression

Return logic was inverted.
Going for changing the return value to not return zero as it is makes
more sense regarding the naming of the function (cpu_has_cpufreq()).

http://bugzilla.kernel.org/show_bug.cgi?id=3410



Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>