ipc: Use the same namespace to modify and validate

ipc: Use the same namespace to modify and validate

In the 1f5c135ee509 ("ipc: Store ipc sysctls in the ipc namespace") I
missed that in addition to the modification of sem_ctls[3], the change
is validated. This validation must occur in the same namespace.

Link: https://lore.kernel.org/lkml/875ymnvryb.fsf@email.froward.int.ebiederm.org/
Fixes: 1f5c135ee509 ("ipc: Store ipc sysctls in the ipc namespace")
Signed-off-by: Alexey Gladkov <legion@kernel.org>
Link: https://lkml.kernel.org/r/b3cb9a25cce6becbef77186bc1216071a08a969b.1651584847.git.legion@kernel.org
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>