sched/nohz: Clean up select_nohz_load_balancer()

sched/nohz: Clean up select_nohz_load_balancer()

There is no load_balancer to be selected now. It just sets the
state of the nohz tick to stop.

So rename the function, pass the 'cpu' as a parameter and then
remove the useless call from tick_nohz_restart_sched_tick().

[ s/set_nohz_tick_stopped/nohz_balance_enter_idle/g
  s/clear_nohz_tick_stopped/nohz_balance_exit_idle/g ]
Signed-off-by: Alex Shi <alex.shi@intel.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1347261059-24747-1-git-send-email-alex.shi@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>