Switch to c++11 enums for flatbuffers

Change-Id: I99171464bf54efbb7eb322c556760dee86648f5e
diff --git a/frc971/control_loops/drivetrain/splinedrivetrain.h b/frc971/control_loops/drivetrain/splinedrivetrain.h
index 4f21b29..b28334c 100644
--- a/frc971/control_loops/drivetrain/splinedrivetrain.h
+++ b/frc971/control_loops/drivetrain/splinedrivetrain.h
@@ -95,7 +95,7 @@
   bool enable_ = false;
   bool output_was_capped_ = false;
 
-  std::atomic<PlanningState> plan_state_ = {PlanningState_NO_PLAN};
+  std::atomic<PlanningState> plan_state_ = {PlanningState::NO_PLAN};
 
   ::std::thread worker_thread_;
   // mutex_ is held by the worker thread while it is doing work or by the main