maemo: remove

The current postmarketOS port does not do Hildon/Maemo Leste justice. Various features are missing or broken. We can't even upgrade to the newest version, because of packaging issues that can't easily be resolved. And nobody is maintaining it currently. So for the people who want to use Hildon, please use Maemo Leste (https://maemo-leste.github.io/).

If somebody is willing to invest a lot of time for a new postmarketOS port of Hildon/Maemo Leste, let us know!

Close: #373 (closed), #512 (closed), #388 (closed), #234 (closed), #78 (closed)