Revert defaults for cpufreq, add module for intel_pstate

Why defaults should be reverted: https://github.com/rickysarraf/laptop-mode-tools/commit/fadb4e13172b2afa470916e24c59078c8ce78a0d#commitcomment-4942472

intel_pstate isn't actually a cpufreq driver. It has built-in governor, it has cpufreq sysfs interface, but it isn't fully working. If we won't touch cpuX/cpufreq/*, we could completely control it through /sys/devices/system/cpu/intel_pstate/*.