Make deviceRegistryNamespace readonly

Author: Molly Iverson

specification/deviceprovisioningservices/resource-manager/Microsoft.Devices/DeviceProvisioningServices/models.tsp

@@ -355,6 +355,7 @@ model IotDpsPropertiesDescription {
   /**
    * The Device Registry namespace that is linked to the provisioning service.
    */
+  @visibility(Lifecycle.Read)
   deviceRegistryNamespace?: DeviceRegistryNamespaceDescription;
 
   /**

specification/deviceprovisioningservices/resource-manager/Microsoft.Devices/DeviceProvisioningServices/preview/2026-06-01-preview/iotdps.json

@@ -2044,7 +2044,8 @@
         },
         "deviceRegistryNamespace": {
           "$ref": "#/definitions/DeviceRegistryNamespaceDescription",
-          "description": "The Device Registry namespace that is linked to the provisioning service."
+          "description": "The Device Registry namespace that is linked to the provisioning service.",
+          "readOnly": true
         },
         "deviceRegistryNamespaces": {
           "type": "object",