mlxsw: spectrum: Send untagged packets through a port netdev

Port netdevs (e.g. swXpY) that are not bridged are represented in the
device using a vPort with VID=PVID=1 (the PVID vPort), as untagged
packets entering the switch are internally tagged with the PVID VLAN.
When these packets are routed through a different port netdev they
should egress untagged.

This wasn't a problem until now, as non-bridged traffic only originated
from the CPU, which transmits packets out of the port as-is.

When a vPort is created with VID 1 mark it as egress untagged.

Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>