cpufreq: CPU max. hardlimit touch for 3.10

This is a derivative of the original hardlimit implementation
* Transfer to new driver locations
* Improve integration with existing code
* Provide conditional parameters
* Allow fully replacing cpufreq_limit
* Fix a missing cpufreq_limit separator
cpufreq: CPU max. hardlimit optional enable

Allow hardlimit to be enabled and disabled from userspace
* Default to disabled due to instability in current version