Revert "cpufreq: Convert the cpufreq_driver_lock to a rwlock"

This reverts commit 09ea667a0b84ed5fa3b7a65cebd073ac099b4ffe.
Revert "cpufreq: Convert the cpufreq_driver_lock to use RCU"

This reverts commit 8374cecb7f11b6a9881ace45332a9eb315502143.