VOL-1941: Use protobufs from the voltha-protos repo, not a copy

- Use protobufs from the voltha-protos repo, not a copy
- Provided option to specify the openolt proto version via make option
- Removed duplicate README.md

Change-Id: Id67714c8119521f8358aaa9245268c47b7e843cf
diff --git a/agent/src/indications.h b/agent/src/indications.h
index c2f0724..f762e72 100644
--- a/agent/src/indications.h
+++ b/agent/src/indications.h
@@ -19,7 +19,7 @@
 #define OPENOLT_INDICATIONS_H_
 
 #include <grpc++/grpc++.h>
-#include <openolt.grpc.pb.h>
+#include <voltha_protos/openolt.grpc.pb.h>
 #include "Queue.h"
 
 extern "C" {