sensors/zones: place in namespace and cleanup

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: I527dbc8477a232945f696227a7b0b2adbee45175
diff --git a/sysfs/sysfswrite.cpp b/sysfs/sysfswrite.cpp
index 93a64dc..db903cb 100644
--- a/sysfs/sysfswrite.cpp
+++ b/sysfs/sysfswrite.cpp
@@ -19,6 +19,9 @@
 #include <fstream>
 #include <iostream>
 
+namespace pid_control
+{
+
 void SysFsWritePercent::write(double value)
 {
     double minimum = getMin();
@@ -45,3 +48,5 @@
 
     return;
 }
+
+} // namespace pid_control