macvlan: Allow setting multicast filter on all macvlan types

macvlan: Allow setting multicast filter on all macvlan types

Currently, macvlan code restricts multicast and unicast
filter setting only to passthru devices.  As a result,
if a guest using macvtap wants to receive multicast
traffic, it has to set IFF_ALLMULTI or IFF_PROMISC.

This patch makes it possible to use the fdb interface
to add multicast addresses to the filter thus allowing
a guest to receive only targeted multicast traffic.

CC: John Fastabend <[email protected]>
CC: Michael S. Tsirkin <[email protected]>
CC: Jason Wang <[email protected]>
Signed-off-by: Vladislav Yasevich <[email protected]>
Acked-by: John Fastabend <[email protected]>
Acked-by: Michael S. Tsirkin <[email protected]>
Signed-off-by: David S. Miller <[email protected]>