UPSTREAM: locking/lockdep, cpu/hotplug: Annotate AP thread

Anybody trying to assert the cpu_hotplug_lock is held (lockdep_assert_cpus_held())
from AP callbacks will fail, because the lock is held by the BP.

Stick in an explicit annotation in cpuhp_thread_fun() to make this work.

Bug: 254441685
Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-tip-commits@vger.kernel.org
Fixes: cb538267ea1e ("jump_label/lockdep: Assert we hold the hotplug lock for _cpuslocked() operations")
Link: http://lkml.kernel.org/r/20180911095127.GT24082@hirez.programming.kicks-ass.net


Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit cb92173d1f0474784c6171a9d3fdbbca0ee53554)
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: Icec321809fb26f4c07a958f678e6465eaaa26c4a