Using upstream openolt.proto

Change-Id: I5ac8f2e1ced4a2a818ee4a106f997f88a526cf9f
diff --git a/go.mod b/go.mod
index afe0e88..515d233 100644
--- a/go.mod
+++ b/go.mod
@@ -5,7 +5,7 @@
 require (
 	github.com/golang/protobuf v1.3.2
 	github.com/looplab/fsm v0.1.0
+	github.com/opencord/voltha-protos v0.0.0-20190813191205-792553b747df
 	github.com/sirupsen/logrus v1.4.2
-	google.golang.org/genproto v0.0.0-20180817151627-c66870c02cf8
 	google.golang.org/grpc v1.22.1
 )