[submodule] Update submodule sonic-dbsyncd to the latest HEAD automat…

…ically (#14739)

#### Why I did it
src/sonic-dbsyncd
```
* d6b2000 - (HEAD -> 202012, origin/202012) Fix the LLDP_LOC_CHASSIS not getting populated if no remote neighbors are present (#39) (#58) (7 months ago) [abdosi]
* 0f8d503 - Use github code scanning instead of LGTM (#55) (8 months ago) [Liu Shilong]
```