sched: Remove synchronize rcu/sched calls from _cpu_down
There is no need for sync_sched() in _cpu_down as stop_machine()
provides that barrier implicitly. Removing it also helps improve
hot-unplug latency.
The sync_sched/rcu were earlier removed for the same reason by the
commit
9ee349ad6d326df3633 ("sched: Fix set_cpu_active() in cpu_down()"),
but recently got added as part of commit <
6acce3ef84520537> ("sched:
Remove get_online_cpus() usage.").
CRs-Fixed:
1048941
Change-Id: I97763004454d082d3cc2d9d9dbef7da923608600
Signed-off-by: Kaushal Kumar <kaushalk@codeaurora.org>
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>
Signed-off-by: Runmin Wang <runminw@codeaurora.org>