nvme-tcp-offload: Add controller level implementation

In this patch we implement controller level functionality including:
- create_ctrl.
- delete_ctrl.
- free_ctrl.

The implementation is similar to other nvme fabrics modules, the main
difference being that the nvme-tcp-offload ULP calls the vendor specific
claim_dev() op with the given TCP/IP parameters to determine which device
will be used for this controller.
Once found, the vendor specific device and controller will be paired and
kept in a controller list managed by the ULP.

Acked-by: Igor Russkikh <irusskikh@marvell.com>
Signed-off-by: Arie Gershberg <agershberg@marvell.com>
Signed-off-by: Prabhakar Kushwaha <pkushwaha@marvell.com>
Signed-off-by: Omkar Kulkarni <okulkarni@marvell.com>
Signed-off-by: Michal Kalderon <mkalderon@marvell.com>
Signed-off-by: Ariel Elior <aelior@marvell.com>
Signed-off-by: Shai Malin <smalin@marvell.com>
Reviewed-by: Himanshu Madhani <himanshu.madhani@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>