ExitAirSensor: Get power readings from PSU

Now that PSU Sensors work, remove todo. Also fix
a bug where a int32 should have been a double as the
value from d-bus is a double.

Tested: Ipmitool sensor list

Change-Id: Ic7b31c1091b8178dc23ca79fdc189b973095a8e3
Signed-off-by: James Feist <james.feist@linux.intel.com>
diff --git a/include/sensor.hpp b/include/sensor.hpp
index 2a414da..3d81f1f 100644
--- a/include/sensor.hpp
+++ b/include/sensor.hpp
@@ -4,6 +4,8 @@
 #include <sdbusplus/asio/object_server.hpp>
 
 constexpr size_t sensorFailedPollTimeMs = 5000;
+
+constexpr const char* sensorValueInterface = "xyz.openbmc_project.Sensor.Value";
 struct Sensor
 {
     Sensor(const std::string& name, const std::string& path,