dt-bindings: net: ethernet-controller: add 10g-qxgmii mode

Add the new interface mode 10g-qxgmii, which is similar to
usxgmii but extend to 4 channels to support maximum of 4
ports with the link speed 10M/100M/1G/2.5G.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: Luo Jie <quic_luoj@quicinc.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>