mm/damon/vaddr: support stat-purpose DAMOS filters

mm/damon/vaddr: support stat-purpose DAMOS filters

This patch extends DAMOS_STAT handling of the DAMON operations sets for
virtual address spaces for ops-level DAMOS filters.  It leverages the
walk_page_range to walk the page table and gets the folio from page table.
The last folio scanned is stored in damos->last_applied to prevent double
counting.

Link: https://lkml.kernel.org/r/264a4b5ea202fd73c01b349c9694d8bf9978c441.1754135312.git.pyyjason@gmail.com
Signed-off-by: Yueyang Pan <pyyjason@gmail.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Usama Arif <usamaarif642@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>