Revert "SMP_IDLE_THREAD fix"

This reverts commit 352842fb5bfef6513812a7d5fe2881191c3c26b5.
Revert "rcu: Use smp_hotplug_thread facility for RCUs per-CPU kthread"

This reverts commit f24ac24663e2a97106d8ddbffacb7ec4d61b7422.
Revert "stop_machine: Mark per cpu stopper enabled early"

This reverts commit bf66373b12014f33ede8eee47333e8bb6ff7f82c.
Revert "stop_machine: Use smpboot threads"

This reverts commit 22e442db68cd2de747bda7b09378f273a006c692.
Revert "stop_machine: Store task reference in a separate per cpu variable"

This reverts commit cb0016cb26f145efe9d6b989024d1767d4dbc7a3.
Revert "kthread: Prevent unpark race which puts threads on the wrong cpu"

This reverts commit f940cbbefdffd08ee9938c15964c60ef9e26a255.
Revert "smpboot: Allow selfparking per cpu threads"

This reverts commit 7b68de15136e89e9ffe8dc116322ee99686dd0ca.
Revert "hotplug: Fix UP bug in smpboot hotplug code"

This reverts commit 07a1fc41b7908185fd133b1f8ba7d4276acc73e5.
Revert "smpboot: Provide infrastructure for percpu hotplug threads"

This reverts commit 2c7f8c3964da503a8160836c2072915c3471e7bb.
Revert "kthread: Implement park/unpark facility"

This reverts commit 4fac42cfc8ad78eb601527621e31419053de4199.
Revert "smpboot, idle: Fix comment mismatch over idle_threads_init()"

This reverts commit a6445efcd604d20481ba135bfbb66f971696083a.
Revert "smpboot, idle: Optimize calls to smp_processor_id() in idle_threads_init()"

This reverts commit 9d4d58d7a9d5f28e10edd682c4f7e0e2e5dca099.
Revert "smp, idle: Allocate idle thread for each possible cpu during boot"

This reverts commit abe91fbbcd4f1f144db5dc18ce078f6bb341c265.
Revert "softirq: Use hotplug thread infrastructure"

This reverts commit f2d9bb543f90a89f2dda06441a8415e54ac3cab8.
Revert "smp: Provide generic idle thread allocation"

This reverts commit ca6254a89c8fadab564eaf465da29b8787a3323a.