mm/damon/core: add damon_reset_aggregated() debug_sanity check

mm/damon/core: add damon_reset_aggregated() debug_sanity check

At time of damon_reset_aggregated(), aggregation of the interval should be
completed, and hence nr_accesses and nr_accesses_bp should match.  I found
a few bugs caused it to be broken in the past, from online parameters
update and complicated nr_accesses handling changes.  Add a sanity check
for that under CONFIG_DAMON_DEBUG_SANITY.

Link: https://lkml.kernel.org/r/20260306152914.86303-9-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: David Gow <davidgow@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>