Update imports to reflect v2 of voltha-lib-go

Go mod complains if a v2 module is not imported using the v2 syntax:

go.mod|14| invalid module: github.com/opencord/voltha-lib-go should be v0 or v1, not v2 (v2.2.3) 

The workaround is to modify `go.mod` with the desired version, run `go mod tidy` and it will replace it with a commit tag. This is inconvenient and does not accurately express the pinned version.

Look into what it will take to resolve this, and hope it does not mean actually structuring our repositories with a `v2` root directory.