rocker: install untagged VLAN (vid=0) support for each port

On port probe, install by default untagged VLAN support.  This is
equivalent to running the command:

	bridge vlan add vid 0 dev DEV self

A user could, if they wanted, manaully removing untagged support from the
port by running the command:

	bridge vlan del vid 0 dev DEV self

But installing it by default on port initialization gives the normal
expected behavior.

Signed-off-by: Scott Feldman <sfeldma@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>