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/motors/usb/usb.h b/motors/usb/usb.h
index 2475220..2b0cf17 100644
--- a/motors/usb/usb.h
+++ b/motors/usb/usb.h
@@ -13,8 +13,7 @@
 #include "motors/usb/constants.h"
 #include "motors/util.h"
 
-namespace frc971 {
-namespace teensy {
+namespace frc971::teensy {
 
 // A sufficient memory barrier between writing some data and telling the USB
 // hardware to read it or having the USB hardware say some data is readable and
@@ -584,7 +583,6 @@
   friend class UsbDevice;
 };
 
-}  // namespace teensy
-}  // namespace frc971
+}  // namespace frc971::teensy
 
 #endif  // MOTORS_USB_USB_H_