ixgbe: Add KR mode support for CS4227 chip

KR auto-neg mode is what we will be using going forward. The SW
interface for this mode is different that what was used for iXFI.

Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>