They're growing to be too many and planned to get split further. Move
them under their own directory.
kernel/cgroup.c -> kernel/cgroup/cgroup.c
kernel/cgroup_freezer.c -> kernel/cgroup/freezer.c
kernel/cgroup_pids.c -> kernel/cgroup/pids.c
kernel/cpuset.c -> kernel/cgroup/cpuset.c
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Acked-by: Zefan Li <lizefan@huawei.com>