Add support for new Kobo Aura H2O and firmware 3.8.0

Kobo have announced a new device. It uses the same firmware as their
other devices. This adds the device id and name.

There is also a new firmware version released. This is version 3.8.0,
but I am allowing 3.8.1. There are no changes needed to support the
firmware.

Fixes #1362435 [Add support for new Kobo Aura H2O and firmware 3.8.0](https://bugs.launchpad.net/calibre/+bug/1362435)