security: support user data retrieval

security: support user data retrieval

In case of inline protocol processed ingress traffic, the packet may not
have enough information to determine the security parameters with which
the packet was processed. In such cases, application could get metadata
from the packet which could be used to identify the security parameters
with which the packet was processed.

Application could register "userdata" with the security session, and
this could be retrieved from the metadata of inline processed packets.
The metadata returned by "rte_security_get_pkt_metadata()" will be
device specific. Also the driver is expected to return the application
registered "userdata" as is, without any modifications.

Signed-off-by: Anoob Joseph <anoob.joseph@caviumnetworks.com>
Acked-by: Akhil Goyal <akhil.goyal@nxp.com>