The client interface is only intended for use on devices that support
iWarp. Only register with the client if this is the case.

This fixes a panic when loading i40iw on X710 devices.
Signed-off-by: NMitch Williams <mitch.a.williams@intel.com>
Reported-by: NStefan Assmann <sassmann@kpanic.de>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>