mm/damon/sysfs: implement refresh_ms file internal work

Only minimum file operations for refresh_ms file is implemented.  Further
implement its designed behavior, the periodic essential files content
update, using repeat mode damon_call().

If non-zero value is written to the file, update DAMON sysfs files for
auto-tuned monitoring intervals, DAMOS stats, and auto-tuned DAMOS quota
values, which are essential to be monitored in most DAMON use cases.  The
user-written non-zero value becomes the time delay between the update.  If
zero is written to the file, the periodic refresh is disabled.

Link: https://lkml.kernel.org/r/20250717055448.56976-3-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>