net/cnxk: support custom SA index

net/cnxk: support custom SA index

Adding cnxk device driver support to configure custom SA index.
Custom SA index can be configured as part of the session create
as SPI, and later original SPI can be updated using session update.

Signed-off-by: Kiran Kumar K <kirankumark@marvell.com>
Acked-by: Ray Kinsella <mdr@ashroe.eu>
Acked-by: Jerin Jacob <jerinj@marvell.com>