Fix another small queue interface issue.

It's a little embarrassing that this made it past all of us in
code review.

Change-Id: I3dee0514e5178293c6c00e85778432c1ff82ed81
diff --git a/frc971/control_loops/fridge/fridge.q b/frc971/control_loops/fridge/fridge.q
index 1abd821..6e09c0b 100644
--- a/frc971/control_loops/fridge/fridge.q
+++ b/frc971/control_loops/fridge/fridge.q
@@ -59,3 +59,5 @@
   queue Output output;
   queue Status status;
 };
+
+queue_group Fridge fridge;