nfp: refresh port state before reporting autonegotiation

State of autonegotiation may have changed but is not yet refreshed.
Make sure ethtool respects the NFP_PORT_CHANGED flag when looking
at autoneg.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>