smp/hotplug: Differentiate the AP-work lockdep class between up and down

With lockdep-crossrelease we get deadlock reports that span cpu-up and
cpu-down chains. Such deadlocks cannot possibly happen because cpu-up
and cpu-down are globally serialized.

  CPU0                  CPU1                    CPU2
  cpuhp_up_callbacks:   takedown_cpu:           cpuhp_thread_fun:

  cpuhp_state
                        irq_lock_sparse()
    irq_lock_sparse()
                        wait_for_completion()
                                                cpuhp_state
                                                complete()

Now that we have consistent AP state, we can trivially separate the
AP-work class between up and down using st->bringup.

Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Link: https://lkml.kernel.org/r/[email protected]

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