bridge: vni: Indent statistics with 2 spaces

bridge: vni: Indent statistics with 2 spaces

`bridge -s vlan` indents statistics with 2 spaces compared to the vlan id
column while `bridge -s vni` indents them with 1 space. Change `bridge vni`
to match the behavior of `bridge vlan` since that second command predates
`bridge vni`.

Before:
$ bridge -s vni
dev               vni                group/remote
vxlan1            4001
                   RX: bytes 0 pkts 0 drops 0 errors 0
                   TX: bytes 0 pkts 0 drops 0 errors 0
                  4002               10.0.0.1
                   RX: bytes 0 pkts 0 drops 0 errors 0
                   TX: bytes 0 pkts 0 drops 0 errors 0
vxlan2            100
                   RX: bytes 0 pkts 0 drops 0 errors 0
                   TX: bytes 0 pkts 0 drops 0 errors 0

After:
$ bridge -s vni
dev               vni                group/remote
vxlan1            4001
                    RX: bytes 0 pkts 0 drops 0 errors 0
                    TX: bytes 0 pkts 0 drops 0 errors 0
                  4002               10.0.0.1
                    RX: bytes 0 pkts 0 drops 0 errors 0
                    TX: bytes 0 pkts 0 drops 0 errors 0
vxlan2            100
                    RX: bytes 0 pkts 0 drops 0 errors 0
                    TX: bytes 0 pkts 0 drops 0 errors 0

Reviewed-by: Petr Machata <petrm@nvidia.com>
Tested-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Benjamin Poirier <bpoirier@nvidia.com>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>