Update to version 4.1.0

Rebases A-wai's work on 4.1.0. This also adds a new patch supporting the fdtdir being on a /boot seperate from /.

As with the last MR, needs to be merged at the same time as https://gitlab.com/mobian1/miniramfs/-/merge_requests/10 (which should be updated to match this version number)

We should decide at some point whether the boot partition detection code should be upstreamed or a config option. The latter seems to be where upstream are going right now.

Additionally, the current configuration leaves a blank line in each config. This does not cause any issues.

Tested on Mobian/PPP.