i40e: Add support for client interface for IWARP driver

This patch adds a Client interface for i40iw driver
support. Also expands the Virtchannel to support messages
from i40evf driver on behalf of i40iwvf driver.

This client API is used by the i40iw and i40iwvf driver
to access the core driver resources brokered by the i40e driver.

Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>