fsl/fman: fix 1G support for QSGMII interfaces

QSGMII ports were not advertising 1G speed.

Signed-off-by: Madalin Bucur <madalin.bucur@nxp.com>
Reviewed-by: Camelia Groza <camelia.groza@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>