main/postmarketos-mkinitfs: backport patches from master
The osk-sdl patch has been in master for quite some time, should be safe to backport. The other one is a new fix that makes sure we don't run out of space on /boot if mkinitfs-extra size increases slightly (shouldn't happen on v21.03, but just to be sure).
- main/postmarketos-mkinitfs: refactor osk-sdl config/running (MR 1870)
- main/postmarketos-mkinitfs: fix space issues (MR 2051)
Trivial backport, merging after CI passes.