Today, interfaces are working in vlan-promisc mode; But once
vlan filtering offloaded would be supported, we'll need a method to
control it directly [e.g., when setting device to PROMISC, or when
running out of vlan credits].

This adds the necessary API for L2 client to manually choose whether to
accept all vlans or only those for which filters were configured.
Signed-off-by: Yuval Mintz <Yuval.Mintz@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>