UPSTREAM: 8755: Fix panic for GetZoneByNodeName on Azure Stack

Azure Stack does not support the API Version, 2020-12-01, for
PlatformFaultDomain, and therefore panics when we run the cloud
provider on Azure Stack. This avoids the panic, but we cannot
get the correct PlatformFaultDomain (which may not be an issue).

Author: patrickdillon

pkg/provider/azure_standard.go

@@ -580,7 +580,11 @@ func (as *availabilitySet) GetZoneByNodeName(ctx context.Context, name string) (
 		failureDomain = as.makeZone(ptr.Deref(vm.Location, ""), zoneID)
 	} else {
 		// Availability zone is not used for the node, falling back to fault domain.
-		failureDomain = strconv.Itoa(int(ptr.Deref(vm.Properties.InstanceView.PlatformFaultDomain, 0)))
+		if prop := vm.Properties; prop == nil || prop.InstanceView == nil {
+			failureDomain = "0"
+		} else {
+			failureDomain = strconv.Itoa(int(ptr.Deref(vm.Properties.InstanceView.PlatformFaultDomain, 0)))
+		}
 	}
 
 	zone := cloudprovider.Zone{