zebra: fix JSON fields for show evpn vni detail

zebra: fix JSON fields for show evpn vni detail

Few of the JSON field in show evpn vni detail command is
confusing and a few fields were missing. Following is the
updated output.

primary# show evpn vni detail json
[
  {
    "vni":200,
    "type":"L2",
    "vrf":"default",
    "tenantVrf":"default",
    "vxlanInterface":"vni200",
    "ifindex":19,
    "vxlanIfindex":19,
    "sviInterface":"br200",
    "sviIfindex":18,
    "vtepIp":"2.2.2.1",
    "mcastGroup":"0.0.0.0",
    "advertiseGatewayMacip":"No",
    "advertiseSviMacip":"No",
    "numMacs":0,
    "numArpNd":0,
    "numRemoteVteps":1,
    "remoteVteps":[
      {
        "ip":"2.2.2.2",
        "flood":"HER"
      }
    ]
  },
  {
    "vni":100,
    "type":"L3",
    "vrf":"default",
    "tenantVrf":"default",
    "localVtepIp":"2.2.2.1",
    "vxlanIntf":"vni100",
    "sviIntf":"br100",
    "state":"Up",
    "sysMac":"aa:bb:cc:dd:ee:f1",
    "routerMac":"aa:bb:cc:dd:ee:f1",
    "vniFilter":"none",
    "l2Vnis":[
      20,
      30,
      200
    ]
  }
]

Signed-off-by: Pooja Jagadeesh Doijode <pdoijode@nvidia.com>