Add limitation that AAD buffer must be padded with zeroes
in GCM case.
Fixes: d4f44265a1d7 ("doc: add limitation of AAD size to QAT guide")
Cc: stable@dpdk.org
Signed-off-by: Fiona Trahe <fiona.trahe@intel.com>
Acked-by: Arek Kusztal <arkadiuszx.kusztal@intel.com>