mm/damon/reclaim: add a parameter called skip_anon for avoiding anonymous pages reclamation

In some cases, for example if users have confidence at anonymous pages
management or the swap device is too slow, users would want to avoid
DAMON_RECLAIM swapping the anonymous pages out.  For such case, add yet
another DAMON_RECLAIM parameter, namely 'skip_anon'.  When it is set as
'Y', DAMON_RECLAIM will avoid reclaiming anonymous pages using a DAMOS
filter.

Link: https://lkml.kernel.org/r/20221205230830.144349-4-sj@kernel.org


Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>