bridge: implement multicast fast leave

V3: make it a flag
V2: make the toggle per-port

Fast leave allows bridge to immediately stops the multicast
traffic on the port receives IGMP Leave when IGMP snooping is enabled,
no timeouts are observed.

Cc: Herbert Xu <[email protected]>
Cc: Stephen Hemminger <[email protected]>
Cc: "David S. Miller" <[email protected]>
Signed-off-by: Cong Wang <[email protected]>
5 files changed