Using upstream openolt.proto

Change-Id: I5ac8f2e1ced4a2a818ee4a106f997f88a526cf9f
diff --git a/Makefile b/Makefile
index 82a57cd..cfb0fc7 100644
--- a/Makefile
+++ b/Makefile
@@ -25,7 +25,7 @@
 
 all: help
 
-protos: api/openolt/openolt.pb.go api/bbsim/bbsim.pb.go # @HELP Build proto files
+protos: api/bbsim/bbsim.pb.go # @HELP Build proto files
 
 build: protos # @HELP Build the binary
 	GO111MODULE=on go build -i -v \