zebra: Add missing json attributes for show evpn

zebra: Add missing json attributes for show evpn

Missing json attributes added for show evpn json

Before:
```
tor-1# show evpn json
{
  "advertiseGatewayMacip":"No",
  "numVnis":26,
  "numL2Vnis":21,
  "numL3Vnis":5,
  "isDuplicateAddrDetection":true,
  "maxMoves":5,
  "detectionTime":180,
  "detectionFreezeTime":0,
  "macHoldtime":1080,
  "neighHoldtime":1080,
  "startupDelay":180,
  "startupDelayTimer":"--:--:--",
  "uplinkConfigCount":0,
  "uplinkActiveCount":0
}
tor-1#
```

After:
```
tor-1# show evpn json
{
  "advertiseGatewayMacip":"No",
  "advertiseSviMacip":"No",
  "advertiseSviMac":"No",
  "numVnis":26,
  "numL2Vnis":21,
  "numL3Vnis":5,
  "isDuplicateAddrDetection":true,
  "maxMoves":5,
  "detectionTime":180,
  "detectionFreezeTime":0,
  "macHoldtime":1080,
  "neighHoldtime":1080,
  "startupDelay":180,
  "startupDelayTimer":"--:--:--",
  "uplinkConfigCount":0,
  "uplinkActiveCount":0
}
tor-1#
```

Ticket:#3323248

Issue:3323248

Testing: UT done

Signed-off-by: Sindhu Parvathi Gopinathan's <sgopinathan@nvidia.com>