sched/fair: Clean up load average references

sched/fair: Clean up load average references

For cfs_rq, we have load.weight, runnable_load_avg, and load_avg.
Clean up how they are used:

  - First, as group sched_entity already largely uses load_avg, we now expand
    to use load_avg in all cases.

  - Second, for CPU-wide load balancing, we choose to use runnable_load_avg
    in all cases, which is the same as before this series.

[Atish]:
Here is the conflict in this patch.
<<<<<<< HEAD
        unsigned long nr_running = ACCESS_ONCE(rq->cfs.h_nr_running);
        unsigned long load_avg = rq->cfs.avg.load_avg;
=======
        unsigned long nr_running = READ_ONCE(rq->cfs.h_nr_running);
        unsigned long load_avg = weighted_cpuload(cpu);
>>>>>>> 7ea241a... sched/fair: Clean up load average references

ACCESS_ONCE is replaced with READ_ONCE by the upstream patch  316c1608d15c7.
As this patch is not in UEK4, ACCESS_ONCE is kept as it is.

Orabug: 25544560

Signed-off-by: Yuyang Du <yuyang.du@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: arjan@linux.intel.com
Cc: bsegall@google.com
Cc: dietmar.eggemann@arm.com
Cc: fengguang.wu@intel.com
Cc: len.brown@intel.com
Cc: morten.rasmussen@arm.com
Cc: pjt@google.com
Cc: rafael.j.wysocki@intel.com
Cc: umgwanakikbuti@gmail.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1436918682-4971-8-git-send-email-yuyang.du@intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
(cherry picked from commit 7ea241afbf4924c58d41078599f7a32ba49fb985)

Conflicts:

	kernel/sched/fair.c

Signed-off-by: Atish Patra <atish.patra@oracle.com>
Acked-by: Vijay Kumar <vijay.ac.kumar@oracle.com>
Signed-off-by: Allen Pais <allen.pais@oracle.com>