The USXGMII driver in SDK was heavily refactored, some bugs have been
fixed and it has switched to use phylink_pcs. Follow up with changes
in SDK driver and sync our on-top-of-mainline driver with the SDK
driver.
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
(cherry picked from commit ba58245e83714de5f47b4b0fc0369930c3661cab)