apparmor: Fix kernel-doc header for verify_dfa_accept_index

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202306141934.UKmM9bFX-lkp@intel.com/


Signed-off-by: John Johansen <john.johansen@canonical.com>