bridge: dump mcast querier per vlan

bridge: dump mcast querier per vlan

Dump the multicast querier state per vlan.
This commit is almost identical to [1].

The querier state can be seen with:

bridge -d vlan global

The options for vlan filtering and vlan mcast snooping have to be enabled
in order to see the output:

ip link set [dev] type bridge mcast_vlan_snooping 1 vlan_filtering 1

The querier state shows the following information for IPv4 and IPv6
respectively:

1) The ip address of the current querier in the network. This could be
   ourselves or an external querier.
2) The port on which the querier was seen
3) Querier timeout in seconds

[1] https://git.kernel.org/pub/scm/network/iproute2/iproute2.git/commit/?id=16aa4494d7fc6543e5e92beb2ce01648b79f8fa2

Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: Fabian Pfitzner <f.pfitzner@pengutronix.de>
Signed-off-by: David Ahern <dsahern@kernel.org>