mm/damon/tests/vaddr-kunit: handle alloc failures on damon_do_test_apply_three_regions()

mm/damon/tests/vaddr-kunit: handle alloc failures on damon_do_test_apply_three_regions()

damon_do_test_apply_three_regions() is assuming all dynamic memory
allocation in it will succeed.  Those are indeed likely in the real use
cases since those allocations are too small to fail, but theoretically
those could fail.  In the case, inappropriate memory access can happen.
Fix it by appropriately cleanup pre-allocated memory and skip the
execution of the remaining tests in the failure cases.

Link: https://lkml.kernel.org/r/20251101182021.74868-18-sj@kernel.org
Fixes: 17ccae8bb5c9 ("mm/damon: add kunit tests")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: David Gow <davidgow@google.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: <stable@vger.kernel.org>	[5.15+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>