sensors/zones: place in namespace and cleanup

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I527dbc8477a232945f696227a7b0b2adbee45175
diff --git a/pid/ec/stepwise.cpp b/pid/ec/stepwise.cpp
index 0a5c0b0..0065228 100644
--- a/pid/ec/stepwise.cpp
+++ b/pid/ec/stepwise.cpp
@@ -20,8 +20,11 @@
 #include <cstddef>
 #include <limits>
 
+namespace pid_control
+{
 namespace ec
 {
+
 double stepwise(const ec::StepwiseInfo& info, double input)
 {
     double value = info.output[0]; // if we are below the lowest
@@ -43,4 +46,6 @@
 
     return value;
 }
-} // namespace ec
\ No newline at end of file
+
+} // namespace ec
+} // namespace pid_control