introduce standby state for host interface

Certain host firmware implementations of this interface have the concept
of a standby/safe state. The host firmware has done it's basic
initialization but it has not executed to the point where it can start
operating system instances. A common use case for this on IBM systems is
when a system is being serviced and the technician wants to log into the
host firmware to check hardware status before continuing to start the
operating systems.

Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
Change-Id: Ie0d0007b6859c8a23df83287ac27f251e2cf9b79
diff --git a/xyz/openbmc_project/State/Host.interface.yaml b/xyz/openbmc_project/State/Host.interface.yaml
index a495e80..ba0c570 100644
--- a/xyz/openbmc_project/State/Host.interface.yaml
+++ b/xyz/openbmc_project/State/Host.interface.yaml
@@ -58,6 +58,12 @@
         - name: 'TransitioningToOff'
           description: >
             Host firmware is transitioning to an Off state
+        - name: 'Standby'
+          description: >
+            Host firmware is in a standby state. It is awaiting a Transition
+            request to On to move to Running. This is an intermediate state
+            that some implementations of this object may move to between Off
+            and Running.
         - name: 'Running'
           description: >
             Host firmware is running