If you are not seeing "Restore from iCloud backup" option when setting up a new DEP-configured iOS 11 device, please check the DEP enrollment profile settings. If "Apple ID and sign-in configuration" is skipped in DEP enrollment profile settings, the device doesn't offer restore from iCloud option. It only shows "Restore from iTunes backup" and "Setup as new iPhone" and optionally "Move data from Android", if that is not skipped in enrollment profile settings.
Therefore if you need to restore from iCloud - you need to
- uncheck this option and save the enrollement profile in DEP page ( https://login.online.miradore.com?View=DeviceEnrollmentProgram )
- assign new enrollment profile to devices
- reset the devices again to receive the new enrollment profile settings
Please check also documentation on Apple's support pages related to supervision and MDM profile removal prevention. If you are restoring backup that was made on the same device, supervision settings come from the backup. If you are restoring to a different device, supervision settings come from DEP enrollment settings.