Add PowerOnHours interface

PowerOnHours interface to tell how many hours the system has been
powered-on.

Partially Resolves openbmc/openbmc#2979

Change-Id: I61b149e38717a389f57c2d881ced7faf823d25a7
Signed-off-by: Nagaraju Goruganti <ngorugan@in.ibm.com>
diff --git a/xyz/openbmc_project/State/PowerOnHours.interface.yaml b/xyz/openbmc_project/State/PowerOnHours.interface.yaml
new file mode 100644
index 0000000..1c68296
--- /dev/null
+++ b/xyz/openbmc_project/State/PowerOnHours.interface.yaml
@@ -0,0 +1,8 @@
+description: >
+    Implement to provide the POH(Power-On-Hours) counter.
+properties:
+    - name: POHCounter
+      type: uint32
+      description: >
+        This counter shows how many hours the system has been running. The value
+        is a cumulative one and includes all working hours since production.