sensors/zones: place in namespace and cleanup

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I527dbc8477a232945f696227a7b0b2adbee45175
diff --git a/pid/fancontroller.hpp b/pid/fancontroller.hpp
index d14aef7..25eebad 100644
--- a/pid/fancontroller.hpp
+++ b/pid/fancontroller.hpp
@@ -8,6 +8,9 @@
 #include <string>
 #include <vector>
 
+namespace pid_control
+{
+
 /*
  * A FanController is a PID controller that reads a number of fans and given
  * the output then tries to set them to the goal values set by the thermal
@@ -45,3 +48,5 @@
     std::vector<std::string> _inputs;
     FanSpeedDirection _direction;
 };
+
+} // namespace pid_control