mm/damon: ask apply_scheme() to report filter-passed region-internal bytes

mm/damon: ask apply_scheme() to report filter-passed region-internal bytes

Some DAMOS filter types including those for young page, anon page, and
belonging memcg are handled by underlying DAMON operations set
implementation, via damon_operations->apply_scheme() interface.  How many
bytes of the region have passed the filter can be useful for DAMOS scheme
tuning and access pattern monitoring.  Modify the interface to let the
callback implementation reports back the number if possible.

Link: https://lkml.kernel.org/r/20250106193401.109161-5-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>