UPSTREAM: sched: loadavg: make calc_load_n() public

UPSTREAM: sched: loadavg: make calc_load_n() public

It's going to be used in a later patch. Keep the churn separate.

Link: http://lkml.kernel.org/r/20180828172258.3185-6-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Suren Baghdasaryan <surenb@google.com>
Tested-by: Daniel Drake <drake@endlessm.com>
Cc: Christopher Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <jweiner@fb.com>
Cc: M(CR) Galbraith <efault@gmx.de>
Cc: Peter Enderborg <peter.enderborg@sony.com>
Cc: RPerry Dunlap <rdunlap@infradead.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vinayak Menon <vinmenon@codeaurora.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit 5c54f5b9edb1aa2eabbb1091c458f1b6776a1896)

Bug: 127712811
Test: lmkd in PSI mode
Change-Id: I50e0cb0dbf20ced329a484493f82ff69ca1ae97a
Signed-off-by: Suren Baghdasaryan <surenb@google.com>