Prepare devlink port related functions to optionally fill up
the extack information which will be used in subsequent patch by port
function attribute(s).
Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>