mm/damon/lru_sort: deduplicate hot/cold schemes generators

damon_lru_sort_new_{hot,cold}_scheme() have quite a lot of duplicates. 
This commit factors out the duplicate to a separate function and use it
for reducing the duplicate.

Link: https://lkml.kernel.org/r/20220913174449.50645-23-sj@kernel.org


Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>