move entities into ipmi::sensor namespace

The object was left in the global namespace, but the type was in the
ipmi::sensor namespace.  Move the object into the namespace.

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: If3aa72ebbae980b0b837c45c8fcbc4b47b7fb742
diff --git a/scripts/writeentity.mako.cpp b/scripts/writeentity.mako.cpp
index 110eca9..04ea87c 100644
--- a/scripts/writeentity.mako.cpp
+++ b/scripts/writeentity.mako.cpp
@@ -5,7 +5,8 @@
 #include <ipmid/types.hpp>
 #include <utility>
 
-using namespace ipmi::sensor;
+namespace ipmi {
+namespace sensor {
 
 extern const EntityInfoMap entities = {
 % for key in entityDict.iterkeys():
@@ -34,3 +35,6 @@
 }},
 % endfor
 };
+
+} // namespace sensor
+} // namespace ipmi