SEBA-345: Upgrade to current gRPC and Protobuf libs

Change-Id: I7167a0a490e38cb40b8bd37da81bf78a8e3a86ea
diff --git a/ponsim/bal_servicer.py b/ponsim/bal_servicer.py
index f036d67..1b7c4d4 100644
--- a/ponsim/bal_servicer.py
+++ b/ponsim/bal_servicer.py
@@ -18,7 +18,8 @@
 from voltha.protos import third_party
 from voltha.protos.ponsim_pb2 import PonSimDeviceInfo
 from google.protobuf.empty_pb2 import Empty
-from voltha.adapters.asfvolt16_olt.protos.bal_pb2 import BalServicer, BalErr
+from voltha.adapters.asfvolt16_olt.protos.bal_pb2_grpc import BalServicer
+from voltha.adapters.asfvolt16_olt.protos.bal_pb2 BalErr
 from voltha.adapters.asfvolt16_olt.protos.bal_errno_pb2 import BAL_ERR_OK
 
 _ = third_party