Fix clean target.

Change-Id: I7a625cd62167e54b9940a937bfc4c9f655d42fc4
diff --git a/Makefile b/Makefile
index 2d09e21..55c6d98 100644
--- a/Makefile
+++ b/Makefile
@@ -233,6 +233,7 @@
 clean: clean-bal
 	rm -f $(OBJS) $(DEPS) $(BUILD_DIR)/openolt
 	rm -rf $(OPENOLT_API_DIR)
+	rm $(BUILD_DIR)/libgrpc.so.5 $(BUILD_DIR)/libgrpc++.so.1 $(BUILD_DIR)/libgrpc++_reflection.so.1
 distclean: distclean-openolt-api distclean-bal
 	rm -rf $(BUILD_DIR)
 -include $(DEPS)