octeontx2-af: add mailbox interface for CPT

On OcteonTX2 SoC, the admin function (AF) is the only one with all
priviliges to configure HW and alloc resources, PFs and it's VFs
have to request AF via mailbox for all their needs. This patch adds
a mailbox interface for CPT PFs and VFs to allocate resources
for cryptography. It also adds hardware CPT AF register defines.

Signed-off-by: Suheil Chandran <schandran@marvell.com>
Signed-off-by: Lukasz Bartosik <lbartosik@marvell.com>
Signed-off-by: Srujana Challa <schalla@marvell.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>