e1000e: Expose MDI-X status via ethtool change

Ethtool is a standard way of getting information about
ethernet interfaces.  We enhance ethtool kernel interface
& e1000e to make the MDI-X status readable via ethtool in
userspace.

Signed-off-by: Chaitanya Lala <clala@riverbed.com>
Signed-off-by: Arthur Jones <ajones@riverbed.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>