ethtool: Add Direct Attach support to connector port reporting

This patch allows a base driver to specify Direct Attach as the
type of port through the ethtool interface.

Signed-off-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>