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/common/core.h b/agent/common/core.h
index 6dee098..ed3ea50 100644
--- a/agent/common/core.h
+++ b/agent/common/core.h
@@ -20,7 +20,7 @@
 
 #include <grpc++/grpc++.h>
 using grpc::Status;
-#include <openolt.grpc.pb.h>
+#include <voltha_protos/openolt.grpc.pb.h>
 
 #include "state.h"
 
@@ -89,7 +89,7 @@
 Status OnuPacketOut_(uint32_t intf_id, uint32_t onu_id, uint32_t port_no, uint32_t gemport_id, const std::string pkt);
 Status ProbeDeviceCapabilities_();
 Status ProbePonIfTechnology_();
-Status UplinkPacketOut_(uint32_t intf_id, const std::string pkt, uint16_t flow_id);
+Status UplinkPacketOut_(uint32_t intf_id, const std::string pkt);
 Status FlowAdd_(int32_t access_intf_id, int32_t onu_id, int32_t uni_id, uint32_t port_no,
                 uint32_t flow_id, const std::string flow_type,
                 int32_t alloc_id, int32_t network_intf_id,