net/mlx5e: Allow vlans on e-switch uplink reps

There are cases (e.g tunneling with vlan on underlay and potentially
more) where this makes sense, so allow that.

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