The *folio_sz in damon_pa_young() will be used(as last_folio_sz) by
__damon_pa_check_access(), so it's need to be updated, fix missing branch.

Link: https://lkml.kernel.org/r/20230308083311.120951-4-wangkefeng.wang@huawei.comSigned-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>