mm/damon/core: split out scheme quota adjustment logic into a new function

mm/damon/core: split out scheme quota adjustment logic into a new function

DAMOS quota adjustment logic in 'kdamond_apply_schemes()', has some amount
of code, and the logic is not so straightforward.  Split it out to a new
function for better readability.

Link: https://lkml.kernel.org/r/20221026225943.100429-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>