This patch implements handlers for ethtool get_link_ksettings and
set_link_ksettings. Helper functions use by these handlers are also
introduced in this patch.

Signed-off-by: Chinh Cao <chinh.t.cao@intel.com>
Signed-off-by: Anirudh Venkataramanan <anirudh.venkataramanan@intel.com>
Tested-by: Tony Brelinski <tonyx.brelinski@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>