Nest some more namespaces

Did someone previously suggest that all namespace had been
nested?  Silly.

Signed-off-by: Stephan Pleines <pleines.stephan@gmail.com>
Change-Id: I22278c1caaeba8b47dc46fb2ed3078c20a11e190
diff --git a/frc971/control_loops/control_loop-tmpl.h b/frc971/control_loops/control_loop-tmpl.h
index 7e20227..d86c97c 100644
--- a/frc971/control_loops/control_loop-tmpl.h
+++ b/frc971/control_loops/control_loop-tmpl.h
@@ -3,8 +3,7 @@
 
 #include "aos/logging/logging.h"
 
-namespace frc971 {
-namespace controls {
+namespace frc971::controls {
 
 // TODO(aschuh): Tests.
 
@@ -91,5 +90,4 @@
   status.CheckSent();
 }
 
-}  // namespace controls
-}  // namespace frc971
+}  // namespace frc971::controls