sensors/zones: place in namespace and cleanup

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I527dbc8477a232945f696227a7b0b2adbee45175
diff --git a/pid/pidloop.cpp b/pid/pidloop.cpp
index 8dc6221..f046c9d 100644
--- a/pid/pidloop.cpp
+++ b/pid/pidloop.cpp
@@ -28,6 +28,9 @@
 #include <thread>
 #include <vector>
 
+namespace pid_control
+{
+
 static void processThermals(PIDZone* zone)
 {
     // Get the latest margins.
@@ -121,3 +124,5 @@
             pidControlLoop(zone, timer, false, ms100cnt);
         });
 }
+
+} // namespace pid_control