i40e: use struct assign instead of memcpy

Use struct assignment rather than an expensive memory copy.

Change-Id: I1d18d510774dfd41a9c1250cdef238a4187528f5
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>