main/postmarketos-mkinitfs: allow osk-sdl user overrides
Depends on https://gitlab.com/postmarketOS/osk-sdl/-/merge_requests/135
Sets the new -o option in osk-sdl to load config overrides from /boot/osk.conf
Depends on https://gitlab.com/postmarketOS/osk-sdl/-/merge_requests/135
Sets the new -o option in osk-sdl to load config overrides from /boot/osk.conf