Call out GPUs using their inventory path

The existing code was calling out GPUs in the metadata
with 'GPU=GPUn' because at the time the GPUs were not
in the inventory.

Now that the GPUs are in the inventory, they can be called
out using their inventory objects which is the correct
way to do it.

Resolves openbmc/openbmc#2869

Change-Id: Ic7b3ac465d482aade532f75ef10cc05df4928767
Signed-off-by: Matt Spinler <spinler@us.ibm.com>
diff --git a/org/open_power/Witherspoon/Fault.metadata.yaml b/org/open_power/Witherspoon/Fault.metadata.yaml
index bea9a8a..c8cdad0 100644
--- a/org/open_power/Witherspoon/Fault.metadata.yaml
+++ b/org/open_power/Witherspoon/Fault.metadata.yaml
@@ -83,13 +83,13 @@
   meta:
     - str: "RAW_STATUS=%s"
       type: string
-    - str: "GPU=%s"
-      type: string
+  inherits:
+    - xyz.openbmc_project.Common.Callout.Inventory
 
 - name: GPUOverTemp
   level: ERR
   meta:
     - str: "RAW_STATUS=%s"
       type: string
-    - str: "GPU=%s"
-      type: string
+  inherits:
+    - xyz.openbmc_project.Common.Callout.Inventory