nfp: propagate port speed from management firmware

In future releases the NIC application firmware may be indifferent to port
speeds - not built for specific port speeds - and consequently it will not
be able to report VF port speeds to the driver without first learning them.
With this change, the driver will pass the speed of physical ports from
management firmware to application firmware, and the latter will copy the
speed of port 0 to all the active VFs. So that the driver can get VF port
speed as before.

The port speed of a VF may be requested from userspace using:

  ethtool <vf-intf>

Signed-off-by: Yinjun Zhang <yinjun.zhang@corigine.com>
Reviewed-by: Louis Peens <louis.peens@corigine.com>
Signed-off-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>