mm/damon/core: fix a comment about damon_set_attrs() call timings

mm/damon/core: fix a comment about damon_set_attrs() call timings

The comment on damon_set_attrs() says it should not be called while the
kdamond is running, but now some DAMON modules like sysfs interface and
DAMON_RECLAIM call it from after_aggregation() and/or
after_wmarks_check() callbacks for online tuning.  Update the comment.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: SeongJae Park <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Steven Rostedt (Google) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>