net/mlx5: Emit port affinity event for multipath offloads

Under multipath offload scheme, as part of handling fib events, emit
mlx5 port affinity event on the enabled ports which will be handled by
the tc offloads code.

Signed-off-by: Roi Dayan <roid@mellanox.com>
Reviewed-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>