Use voltha-protos version 4.0.2
Bump major version of voltha-lib-go to 4.0.0 as this change results
in incompatible API version compared to previous version

Change-Id: I1def58361fb1d85f07d6948ebf1ffb7a92eb0d4c
diff --git a/pkg/grpc/common.go b/pkg/grpc/common.go
index d873069..5f90da9 100644
--- a/pkg/grpc/common.go
+++ b/pkg/grpc/common.go
@@ -16,7 +16,7 @@
 package grpc
 
 import (
-	"github.com/opencord/voltha-lib-go/v3/pkg/log"
+	"github.com/opencord/voltha-lib-go/v4/pkg/log"
 )
 
 var logger log.CLogger