VOL-1381 and VOL-1091 Add feature to collect PMmetrics of OLT, this will collect Tx and Rx and posts to kafka. This commit is also related to changes of commit 72b25abd4e804596413558ef10f098c2262dd65d voltha-go
Updated review comments

Updated with code optimization
Updated with dep files
Updated fix for sanity test
Updated with gomod changes

Change-Id: I899e855812a6eda812c64664a9154321cdb16876
diff --git a/go.mod b/go.mod
index e8e0e4a..8cf4b4b 100644
--- a/go.mod
+++ b/go.mod
@@ -7,7 +7,7 @@
 	github.com/golang/protobuf v1.3.2
 	github.com/onsi/ginkgo v1.8.0 // indirect
 	github.com/onsi/gomega v1.5.0 // indirect
-	github.com/opencord/voltha-lib-go/v2 v2.2.7
+	github.com/opencord/voltha-lib-go/v2 v2.2.8
 	github.com/opencord/voltha-protos v1.0.3
 	go.etcd.io/etcd v0.0.0-20190930204107-236ac2a90522
 	google.golang.org/grpc v1.24.0