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/peripheral/adc.h b/motors/peripheral/adc.h
index c22a856..22db93a 100644
--- a/motors/peripheral/adc.h
+++ b/motors/peripheral/adc.h
@@ -5,8 +5,7 @@
 
 #include "motors/util.h"
 
-namespace frc971 {
-namespace motors {
+namespace frc971::motors {
 
 enum class AdcChannels {
   kA,
@@ -15,7 +14,6 @@
 void AdcInitCommon(AdcChannels adc0_channels = AdcChannels::kB,
                    AdcChannels adc1_channels = AdcChannels::kB);
 
-}  // namespace motors
-}  // namespace frc971
+}  // namespace frc971::motors
 
 #endif  // MOTORS_PERIPHERAL_ADC_H_