bgpd: cosmetic changes for debug

bgpd: cosmetic changes for debug

Two changes for debug log -
1. Display empty VRF as "None".
2. Correct wrong "type-2" word for type-3 route.

Before:
```
2023/01/17 04:00:30 BGP: [Z5AV7-75RTE] VRF   vni 100 type-2 route evp [3]:[0]:[32]:[88.88.88.88] RMAC 00:00:00:00:00:00 nexthop 88.88.88.88 esi (null)
```

After:
```
2023/01/17 04:05:24 BGP: [M3X4Y-24DVB] VRF None vni 100 type-3 route evp [3]:[0]:[32]:[88.88.88.88] RMAC 00:00:00:00:00:00 nexthop 88.88.88.88 esi (null)
```

Signed-off-by: anlan_cs <vic.lan@pica8.com>