Factor the per-zone arithemetic inside setup_per_zone_inactive_ratio()'s
loop into a a separate function, calculate_zone_inactive_ratio().  This
function will be used in a later patch

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NMinchan Kim <minchan.kim@gmail.com>
Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>