mm/damon/core: add damos_filter->allow field

DAMOS filters work as only exclusive (reject) filters.  This makes it easy
to be confused, and restrictive at combining multiple filters for covering
various types of memory.

Add a field named 'allow' to damos_filter.  The field will be used to
indicate whether the filter should work for inclusion or exclusion.  To
keep the old behavior, set it as 'false' (work as exclusive filter) by
default, from damos_new_filter().

Following two commits will make the core and operations set layers, which
handles damos_filter objects, respect the field, respectively.

Link: https://lkml.kernel.org/r/20250109175126.57878-3-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>