restore-policy: add option to do nothing

There are two use cases where this new option could be useful:

1) The user of the system wants to simply disable the power restore
   logic.

2) The system implementer wishes to implement a one_time option for this
   D-Bus property. The default for the one_time implementation can be
   this new "None" option so the code logic knows to look at the
   non-one_time setting. If the one_time implementation is not "None"
   then the firmware knows to honor it and reset it to "None".

IBM has a use case for option 2 above. They wish to utilize a one_time
option of this property to cause an automatic power on after an in-band
firmware update.

Signed-off-by: Andrew Geissler <geissonator@yahoo.com>
Change-Id: I59ccf5ff8c0bd3b6e71f6a97e30f2f0feb78d165
diff --git a/xyz/openbmc_project/Control/Power/RestorePolicy.interface.yaml b/xyz/openbmc_project/Control/Power/RestorePolicy.interface.yaml
index 1f90937..d44e09e 100644
--- a/xyz/openbmc_project/Control/Power/RestorePolicy.interface.yaml
+++ b/xyz/openbmc_project/Control/Power/RestorePolicy.interface.yaml
@@ -6,6 +6,7 @@
 properties:
     - name: PowerRestorePolicy
       type: enum[self.Policy]
+      default: 'Restore'
       description: >
           The policy to adopt after the BMC reset.
 
@@ -14,12 +15,15 @@
       description: >
         Possible power restoration policies.
       values:
+        - name: None
+          description: >
+            Perform no power restore logic.
         - name: AlwaysOn
           description: >
             Perform a complete power on process.
         - name: AlwaysOff
           description: >
-            Remain powered off.
+            Perform a complete power off process.
         - name: Restore
           description: >
             Restore power to last requested state recorded before the BMC was