mlxsw: spectrum_switchdev: Allow port enslavement to a VLAN-unaware bridge

Up until now we only allowed VLAN devices to be put in a VLAN-unaware
bridge, but some users need the ability to enslave physical ports as
well.

This is achieved by mapping the port and VID 1 to the bridge's vFID,
instead of the port and the VID used by the VLAN device.

The above is valid because as long as the port is not enslaved to a
bridge, VID 1 is guaranteed to be configured as PVID and egress
untagged.

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