Add a new variable, hw.phy.link_info.an_enabled, to track whether autoneg is
enabled.  Also add a new function update_link_info that will update that
variable as well as calling get_link_info to update the rest of the link info.
Also add get_phy_capabilities to support this.

Change-ID: I5157ef03492b6dd8ec5e608ba0cf9b0db9c01710
Signed-off-by: Catherine Sullivan <catherine.sullivan@intel.com>
Tested-by: Jim Young <jamesx.m.young@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>