drivers: net: aquantia: use XFI, USXGMII interface types

drivers: net: aquantia: use XFI, USXGMII interface types

The PHY supports XFI and USXGMII, the notable difference being that USX AN
is enabled for USXGMII.  Legacy code uses XGMII for any 10G proto and
detects whether USX AN should be enabled or not using a PHY status
register.  Keep that functionality too, so we don't break existing drivers.

Signed-off-by: Razvan Ionut Cirjan <razvanionut.cirjan@nxp.com>
Signed-off-by: Alex Marginean <alexandru.marginean@nxp.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>