mm/damon/sysfs-schemes: call missing mem_cgroup_iter_break()

damon_sysfs_memcg_path_to_id() breaks mem_cgroup_iter() loop without
calling mem_cgroup_iter_break().  This leaks the cgroup reference.  Fix
the issue by calling mem_cgroup_iter_break() before the break.

The issue was discovered [1] by Sashiko.

Link: https://lore.kernel.org/20260426173625.86521-1-sj@kernel.org
Link: https://lore.kernel.org/20260423004148.74722-1-sj@kernel.org [1]
Fixes: 29cbb9a ("mm/damon/sysfs-schemes: implement scheme filters")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> # 6.3.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: sjp38

mm/damon/sysfs-schemes.c

@@ -2594,6 +2594,7 @@ static int damon_sysfs_memcg_path_to_id(char *memcg_path, u64 *id)
 		if (damon_sysfs_memcg_path_eq(memcg, path, memcg_path)) {
 			*id = mem_cgroup_id(memcg);
 			found = true;
+			mem_cgroup_iter_break(NULL, memcg);
 			break;
 		}
 	}