i40e/i40evf: Remove unused variable an_enable and function update_link_info

An_enable was never used only set so lets remove it. The function
update_link_info only did two things, call get_link_info and set
an_enabled. Therefore we should also remove update_link_info and
change all references to it to get_link_info.

Change-ID: Ie3022680fa7a94bfd495a4f5fc76a73701d85569
Signed-off-by: Catherine Sullivan <catherine.sullivan@intel.com>
Tested-by: Jim Young <james.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>