i40e: Fix incorrect return types

Fix return types from i40e_status to enum i40e_status_code.

Signed-off-by: Doug Dziggel <douglas.a.dziggel@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>