add support of IFF_XMIT_DST_RELEASE bit in vlan

add support of IFF_XMIT_DST_RELEASE bit in vlan

Some time ago Eric Dumazet suggested a "hack the IFF_XMIT_DST_RELEASE
flag on the vlan netdev". But the last comment was "does not support
properly bonding/team.(If the real_dev->privflags IFF_XMIT_DST_RELEASE
bit changes, we want to update all the vlans at the same time )"

I've extended that patch to support changes of IFF_XMIT_DST_RELEASE in
bonding/team.
Both bonding and team call netdev_change_features() after recalculation
of features including priv_flags IFF_XMIT_DST_RELEASE bit. So the only
thing needed to support is to recheck this bit in
vlan_transfer_features().

Suggested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Vadim Fedorenko <vfedorenko@yandex-team.ru>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>