net: vlan: announce STAG offload capability in some drivers

- macvlan: propagate STAG filtering capabilities from underlying device
- ifb: announce STAG tagging support in addition to CTAG tagging support
- veth: announce STAG tagging/stripping support in addition to CTAG support

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc drivers/net/ifb.c
Simple merge

diff --cc drivers/net/macvlan.c
Simple merge

diff --cc drivers/net/veth.c
Simple merge