i40e/i40evf: Fix code to accommodate i40e_register.h changes

Remove use of registers no longer supported.

Change-ID: I9d27399091cea78a926489d94f958edd762f5a20
Signed-off-by: Anjali Singhai Jain <anjali.singhai@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>