ipmi-sensor: Add power supply derating factor

Add the power supply derating factor sensor to the ipmi yaml file.
This sensor was currently hardcoded in the /org/openbmc/sensors
path but that is being deprecated in favor of having the sensors
defined in the ipmi yaml config files.

Tested:
With this change the get sensor command was successful.

Change-Id: I7ce1782351871b589e286705523cdcfc86b2f30d
Signed-off-by: Adriana Kobylak <anoo@us.ibm.com>
diff --git a/recipes-phosphor/ipmi/phosphor-ipmi-sensor-inventory-mrw-config/config.yaml b/recipes-phosphor/ipmi/phosphor-ipmi-sensor-inventory-mrw-config/config.yaml
index 45fa20a..ec82afe 100644
--- a/recipes-phosphor/ipmi/phosphor-ipmi-sensor-inventory-mrw-config/config.yaml
+++ b/recipes-phosphor/ipmi/phosphor-ipmi-sensor-inventory-mrw-config/config.yaml
@@ -343,3 +343,14 @@
         Offsets:
           0xFF:
             type: int64_t
+ps_derating_sensor:
+  serviceInterface: org.freedesktop.DBus.Properties
+  readingType: assertion
+  mutability: Mutability::Read
+  sensorNamePattern: nameProperty
+  interfaces:
+    xyz.openbmc_project.Control.PowerSupplyAttributes:
+      DeratingFactor:
+        Offsets:
+          0xFF:
+            type: uint32_t