cgroup:namespace: Remove unused cgroup_namespaces_init()

stable inclusion
from stable-v5.10.195
commit 629079f502fbe214af647fed917d5a1c0165d433
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I95JOC

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=629079f502fbe214af647fed917d5a1c0165d433



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

[ Upstream commit 82b90b6c ]

cgroup_namspace_init() just return 0. Therefore, there is no need to
call it during start_kernel. Just remove it.

Fixes: a79a908f ("cgroup: introduce cgroup namespaces")
Signed-off-by: Lu Jialin <lujialin4@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>