Add 'utilization' sensor to 'Sensors' page

Recent change to xyz.openbmc_project.Sensor.Value interface has
introduced new type of sensor - 'utilization'.

This change makes bmcweb able to expose this kind of sensors in Sensors
schema under /Chassis/{}/Sensors.

Testing:
- implemented simple mocked sensor and verified that:
-- sensor appears in /Chassis/{}/Sensors
-- sensor values are properly shown in /Chassis/{}/Sensors/{}
-- 'ReadingUnits' is shown in /Chassis/{}/Sensors/{}
- RedfishServiceValidator passed

Change-Id: I9e4dc0b9db049a9815e79a0a64df60f275eeb822
Signed-off-by: Adrian Ambrożewicz <adrian.ambrozewicz@linux.intel.com>
diff --git a/redfish-core/lib/sensors.hpp b/redfish-core/lib/sensors.hpp
index b158c78..35b3127 100644
--- a/redfish-core/lib/sensors.hpp
+++ b/redfish-core/lib/sensors.hpp
@@ -764,6 +764,10 @@
         {
             sensor_json["ReadingUnits"] = "Amperes";
         }
+        else if (sensorType == "utilization")
+        {
+            sensor_json["ReadingUnits"] = "Percent";
+        }
     }
     else if (sensorType == "temperature")
     {
@@ -2869,7 +2873,8 @@
   private:
     std::vector<const char*> typeList = {
         "/xyz/openbmc_project/sensors/power",
-        "/xyz/openbmc_project/sensors/current"};
+        "/xyz/openbmc_project/sensors/current",
+        "/xyz/openbmc_project/sensors/utilization"};
     void doGet(crow::Response& res, const crow::Request& req,
                const std::vector<std::string>& params) override
     {