mm/page_owner: align with pageblock_nr_pages

mm/page_owner: align with pageblock_nr_pages

Currently, init_pages_in_zone() walks the zone in pageblock_nr_pages
steps.  MAX_ORDER_NR_PAGES is possible to have holes when
CONFIG_HOLES_IN_ZONE is set.  it is likely to be different between
MAX_ORDER_NR_PAGES and pageblock_nr_pages.  if we skip the size of
MAX_ORDER_NR_PAGES, it will result in the second 2M memroy leak.

Meanwhile, the change will make the code consistent.  because the entire
function is based on the pageblock_nr_pages steps.

Link: http://lkml.kernel.org/r/1512395284-13588-1-git-send-email-zhongjiang@huawei.com
Signed-off-by: zhong jiang <zhongjiang@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>