mm/damon/core: let goal specified with only target and current values

DAMOS quota auto-tuning feature let users to set the goal by providing a
function for getting the current score of the tuned quota.  It allows
flexible goal setup, but only simple user-set quota is currently being
used.  As a result, the only user of the DAMOS quota auto-tuning is using
a silly void pointer casting based score value passing function.  Simplify
the interface and the user code by letting user directly set the target
and the current value.

Link: https://lkml.kernel.org/r/20240219194431.159606-12-sj@kernel.org


Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>