mm/damon/reclaim: deduplicate 'commit_inputs' handling

DAMON_RECLAIM's handling of 'commit_inputs' parameter is duplicated in
'after_aggregation()' and 'after_wmarks_check()' callbacks.  This commit
deduplicates the code for better maintenance.

Link: https://lkml.kernel.org/r/20220606182310.48781-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>