rcu: Kick rcuo kthreads after their CPU goes offline

If a no-CBs CPU were to post an RCU callback with interrupts disabled
after it entered the idle loop for the last time, there might be no
deferred wakeup for the corresponding rcuo kthreads.  This commit
therefore adds a set of calls to do_nocb_deferred_wakeup() after the
CPU has gone completely offline.

CRs-Fixed: 1088159
Change-Id: I97ed8092516d678b172d84fde8cf2958ddae9e45
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Git-commit: 776d680711f4836964f3005ee53794661ca74629
Git-repo: https://github.com/torvalds/linux.git


Signed-off-by: Imran Khan <kimran@codeaurora.org>