LSM: fix documentation for the msg_queue_* hooks

The msg_queue_* hooks were changed in the commit
"msg/security: Pass kern_ipc_perm not msg_queue into the msg_queue
security hooks" (d8c6e854). The type of the argument msq was changed
from msq_queue to kern_ipc_perm. This patch updates the documentation
for the hooks accordingly.

Signed-off-by: Denis Efremov <efremov@ispras.ru>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: James Morris <james.morris@microsoft.com>