selftests/damon: add tests for DAMON_RECLAIM's enabled parameter

mainline inclusion
from mainline-v6.2-rc6
commit 4cc0ee77
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I6MRUG

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4cc0ee7787d7dc595752a8de2e073efa68f7c965

--------------------------------

Add simple test cases for DAMON_RECLAIM's 'enabled' parameter.  Those
tests are focusing on the synchronous behavior of DAMON_RECLAIM enabling
and disabling.

Link: https://lkml.kernel.org/r/20221025173650.90624-3-sj@kernel.org


Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ze Zuo <zuoze1@huawei.com>