net: dsa: bcm_sf2: Support specifying VLAN tag egress rule

The port to which the ASP is connected on 7278 is not capable of
processing VLAN tags as part of the Ethernet frame, so allow an user to
configure the egress VLAN policy they want to see applied by purposing
the h_ext.data[1] field. Bit 0 is used to indicate that 0=tagged,
1=untagged.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>