LSM: fix documentation for the sem_* hooks

The sem_* hooks were changed in the commit
"sem/security: Pass kern_ipc_perm not sem_array into the
sem security hooks" (aefad959

). The type of the argument
sma was changed from sem_array 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>