autoreboot: define new one_time auto reboot prop

IBM has a use case where boots of a system can be done utilizing a debug
tool called istep. This tool does not utilize the normal systemd targets
to boot the system, but instead launches each individual step required
to boot the system. This allows fine grained control of the boot and the
ability to easily debug issues.

When booting a system using this tool, it is required that the automated
reboot policy be off. The issue is that istep can easily set AutoReboot
to false when it is used, but there is no way for it to know when to reset
it to true (i.e. when the user is done).

AutoReboot is a user setting and is something that must stay persistent
based on the users selection. It should not be moved back and forth by
software based on different debug modes.

The solution proposed here is to make a one-time AutoReboot property.
Boot debug tools like istep can utilize this temporary property and be
confident it will be reset whenever the user powers down their system or
stops their host.

Software will first look at this new one-time reboot property. If false
then auto reboots will be disabled. If the temporary reboot property is
true then software will look at the user-based AutoReboot property for
direction.

This new property will have no impact to existing software unless it
gets set and something looks at it. The thought is this could be useful
to more then IBM, so proposing it initially in meta-phosphor.

(From meta-phosphor rev: 7d29e7a2c135e91b222c57c66bb7ca61aae6398e)

Change-Id: I7c542469135061c5b5017b87cffc92aa6b8794c4
Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
diff --git a/meta-phosphor/recipes-phosphor/settings/phosphor-settings-defaults/defaults.yaml b/meta-phosphor/recipes-phosphor/settings/phosphor-settings-defaults/defaults.yaml
index 2545815..f2df02d 100644
--- a/meta-phosphor/recipes-phosphor/settings/phosphor-settings-defaults/defaults.yaml
+++ b/meta-phosphor/recipes-phosphor/settings/phosphor-settings-defaults/defaults.yaml
@@ -10,6 +10,12 @@
           AutoReboot:
              Default: 'true'
 
+/xyz/openbmc_project/control/host0/auto_reboot/one_time:
+    - Interface: xyz.openbmc_project.Control.Boot.RebootPolicy
+      Properties:
+          AutoReboot:
+             Default: 'true'
+
 /xyz/openbmc_project/control/host0/boot:
     - Interface: xyz.openbmc_project.Control.Boot.Source
       Properties: