mm/damon/paddr: minor refactor of damon_pa_pageout()

mm/damon/paddr: minor refactor of damon_pa_pageout()

Patch series "mm/damon/paddr: minor code improvement", v3.

Unify folio_put() to make code more clear, and also fix minor issue in
damon_pa_young().

This patch (of 3):

Omit three lines by unified folio_put(), and make code more clear.

Link: https://lkml.kernel.org/r/20230308083311.120951-1-wangkefeng.wang@huawei.com
Link: https://lkml.kernel.org/r/20230308083311.120951-2-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>