redfish:systems: Handle power restore policy of "None"

On the Control.Power.RestorePolicy interface, a value of "None" is
allowed on the PowerRestorePolicy property and Redfish should handle
this value instead of throwing an internal error. Until support of
"None" as a one time parameter is included into the Redfish schema,
return "AlwaysOff" to align with the dbus interface.

Tested:
  Set PowerRestorePolicy to "None" enum value
  Verified `PowerRestorePolicy` value is "AlwaysOff" thru Redfish
  Set PowerRestorePolicy to "AlwaysOff" enum value
  Verified `PowerRestorePolicy` value is "AlwaysOff" thru Redfish
  Ran Redfish validator:

	Elapsed time: 0:02:47
	invalidPropertyValue: 44
	metadataNamespaces: 2390
	pass: 4384
	passAction: 10
	passGet: 212
	passRedfishUri: 170
	repeat: 1
	skipNoSchema: 3
	skipOptional: 4530
	warnDeprecated: 319
	warningPresent: 64
	Validation has succeeded.

Signed-off-by: Matthew Barth <msbarth@us.ibm.com>
Change-Id: Idb5b16ae797527b9d35a58aa3c26f6527aa5436d
diff --git a/redfish-core/lib/systems.hpp b/redfish-core/lib/systems.hpp
index ec4db21..ca85098 100644
--- a/redfish-core/lib/systems.hpp
+++ b/redfish-core/lib/systems.hpp
@@ -1207,7 +1207,10 @@
                 {"xyz.openbmc_project.Control.Power.RestorePolicy.Policy.AlwaysOff",
                  "AlwaysOff"},
                 {"xyz.openbmc_project.Control.Power.RestorePolicy.Policy.Restore",
-                 "LastState"}};
+                 "LastState"},
+                // Return `AlwaysOff` when power restore policy set to "None"
+                {"xyz.openbmc_project.Control.Power.RestorePolicy.Policy.None",
+                 "AlwaysOff"}};
 
             auto policyMapsIt = policyMaps.find(policy);
             if (policyMapsIt == policyMaps.end())