Merge branch 'bridge-vlan-stats' into next

Petr Machata  says:

====================

ip stats displays bridge-related multicast and STP stats, but not VLAN
stats. There is code for requesting, decoding and formatting these stats
accessible through `bridge -s vlan', but the `ip stats' suite lacks it. In
this patchset, extract the `bridge vlan' code to a generally accessible
place and extend `ip stats' to use it.

This reuses the existing display and JSON format, and plugs it into the
existing `ip stats' hierarchy:

 # ip stats show dev v2 group xstats_slave subgroup bridge suite vlan
 2: v2: group xstats_slave subgroup bridge suite vlan
                   10
                     RX: 3376 bytes 50 packets
                     TX: 2824 bytes 44 packets

                   20
                     RX: 684 bytes 7 packets
                     TX: 0 bytes 0 packets

 # ip -j -p stats show dev v2 group xstats_slave subgroup bridge suite vlan
 [ {
         "ifindex": 2,
         "ifname": "v2",
         "group": "xstats_slave",
         "subgroup": "bridge",
         "suite": "vlan",
         "vlans": [ {
                 "vid": 10,
                 "rx_bytes": 3376,
                 "rx_packets": 50,
                 "tx_bytes": 2824,
                 "tx_packets": 44
             },{
                 "vid": 20,
                 "rx_bytes": 684,
                 "rx_packets": 7,
                 "tx_bytes": 0,
                 "tx_packets": 0
             } ]
     } ]

Similarly for the master stats:

 # ip stats show dev br1 group xstats subgroup bridge suite vlan
 211: br1: group xstats subgroup bridge suite vlan
                   10
                     RX: 3376 bytes 50 packets
                     TX: 2824 bytes 44 packets

                   20
                     RX: 684 bytes 7 packets
                     TX: 0 bytes 0 packets

 # ip -j -p stats show dev br1 group xstats subgroup bridge suite vlan
 [ {
         "ifindex": 211,
         "ifname": "br1",
         "group": "xstats",
         "subgroup": "bridge",
         "suite": "vlan",
         "vlans": [ {
                 "vid": 10,
                 "flags": [ ],
                 "rx_bytes": 3376,
                 "rx_packets": 50,
                 "tx_bytes": 2824,
                 "tx_packets": 44
             },{
                 "vid": 20,
                 "flags": [ ],
                 "rx_bytes": 684,
                 "rx_packets": 7,
                 "tx_bytes": 0,
                 "tx_packets": 0
             } ]
     } ]

====================

Signed-off-by: David Ahern <dsahern@kernel.org>