i40e: Change wording to be more consistent

Change "spoofck" to "spoofchk" to be consistent with as defined in netdev.

Change-ID: I9866d6284cb5f92c8d71dc0776c6d1e71dfb62a5
Signed-off-by: Serey Kong <serey.kong@intel.com>
Tested-by: Jim Young <jamesx.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>