misc: Revert of the following thread parking commits:

* rcu: Use smp_hotplug_thread facility for RCUs per-CPU kthread
* softirq: Use hotplug thread infrastructure
* smp: Add generic smpboot facility
* smp: Provide generic idle thread allocation
* smp, idle: Allocate idle thread for each possible cpu during boot
* smpboot, idle: Optimize calls to smp_processor_id() in idle_threads_init()
* smpboot, idle: Fix comment mismatch over idle_threads_init()
* kthread: Implement park/unpark facility
* smpboot: Provide infrastructure for percpu hotplug threads
* hotplug: Fix UP bug in smpboot hotplug code
* smpboot: Allow selfparking per cpu threads
* kthread: Prevent unpark race which puts threads on the wrong cpu
* stop_machine: Store task reference in a separate per cpu variable
* stop_machine: Use smpboot threads
* stop_machine: Mark per cpu stopper enabled early
* cpufreq: ondemand: Use hotplug thread infrastructure
* cpufreq: ondemand: Remove unused waitqueue
* cpufreq: cpu-boost: Use hotplug thread infrastructure
* cpufreq: cpu-boost: Fix queue_delayed_work_on() race with hotplug
* cpufreq: cpu-boost: Remove unused waitqueue

Change-Id: I360bd13f3d27a5b031f6f51bc0c9e0b9722c045f