v1 of this series was sent in July 2020 by Vasily Khoruzhick.
I have tested it to work on the Pinebook.
Changelog:
v2:
* Rebase
* Add uart-has-rtscts to device tree as requested by reviewer
v3:
* Drop the device tree as it was split out and is already integrated.
* Rename the quirk as requested by reviewer Marcel Holtmann
v4:
* Use skb_pull_data as requested by reviewer Luiz Augusto von Dentz
v5:
* Make use of skb_pull_data's length check