mm/damon/core: introduce repeat mode damon_call()

mm/damon/core: introduce repeat mode damon_call()

damon_call() can be useful for reading or writing DAMON internal data for
one time.  A common pattern of DAMON core usage from DAMON modules is
doing such reads and writes repeatedly, for example, to periodically
update the DAMOS stats.  To do that with damon_call(), callers should call
damon_call() repeatedly, with their own delay loop.  Each caller doing
that is repetitive.  Introduce a repeat mode damon_call().  Callers can
use the mode by setting a new field in damon_call_control.  If the mode is
turned on, damon_call() returns success immediately, and DAMON repeats
invoking the callback function inside the kdamond main loop.

Link: https://lkml.kernel.org/r/20250712195016.151108-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>