RDMA/efa: Add the com service API definitions

Header file for the various commands that can be sent through admin queue.
This includes queue create/modify/destroy, setting up and remove
protection domains, address handlers, and memory registration, etc.

Signed-off-by: Gal Pressman <galpress@amazon.com>
Reviewed-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>