Description

Steps to reproduce the issue:

1. Load later master image(.345) , with SNMP docker build off of SNMP master branch code compiled using sonic-py-swsssdk from master branch.
2. Once SNMP service comes up, view syslog to look for snmp error.

Describe the results you received:

syslog has error message:
raise UnavailableDataError(message, _hash)#012swsssdk.exceptions.UnavailableDataError: Key 'b'COUNTERS:oid:0x60000000005a1'' unavailable in database '2'

The counters DB does not have counter for any of the RIF SAI IDs

Seen after #133

Describe the results you expected:
The unavailable data error should not be visible.

Additional information you deem important (e.g. issue happens only occasionally):

**Output of `show version`:**

```
(paste your output here)
```

**Attach debug file `sudo generate_dump`:**

```
(paste your output here)
```