board/MynaPlayer odyssey: use the version stamp file instead of directly calling git describe in post-image. ...

This is saner, as it allows the build to function properly even outside the external tree (i.e: if make is running from the top level buildroot directory, and not inside the external tree, with an out of tree build).

board/MynaPlayer odyssey: copy the version stamp file into the target.

board/MynaPlayer odyssey: remove rauc partition from genimage, and reworked the overlay filesystem creation. ...

The rauc partition was not needed seeing we make use of a large overlay filesystem. Remove it.

The fstab is now an empty file, so we avoid the original buildroot one.

The rauc-marking-good.service now runs mkdir -p to create the /rauc directory before it marks the slot good.

Also, the post-image script was modified to no longer create filesystems using fallocate. This was honestly dirty and added one more dependency in building MynaPlayer.

Genimage now takes care of creating the overlay filesystem instead.

board/MynaPlayer odyssey: some tweaks to post-image script and genimage template. ...

Added overlay filesystem creation into post-image script and included it  in genimage template.

Also fix bootloader partition size.

board/MynaPlayer odyssey: changed the way the file name and metadata of the images are constructed. ...

Currently, the envsubst tool substitutes the system date and a unique build ID generated with uuidgen.

This commit changes both the template for genimage and the post-image rootfs script to use git describe instead.

board/MynaPlayer odyssey: removed initramfs. ...

This build no longer requires an initramfs. It has hence been removed entirely. The associated defconfig is deleted, as are the postbuild and postimage scripts and overlays. The patches have been relocated to the rootfs_patches directory. Also worth noting is that the machine-id setup is entirely gone from the build system.

board/MynaPlayer odyssey: only copy machine-id into the target with postbuild scripts. Use a device table file to alter its permissions later -- this avoids getting a permission denied error if you have to run the postbuild script multiple times e.g: build errors with trying multiple fixes.

Reworked certificates handling. The certs.sh.example contains a full example of this, and must be copied to certs.sh, and modified accordingly to reflect the real paths where the certificates are stored. A script that can be called by any board is creating symlinks from the real paths to corresponding statics targets for usage in genimage and postbuild scripts. The certs folder in the external tree must never be distributed in the repository, and is hence ignored via .gitignore.

board/MynaPlayer odyssey: copy rauc's keyring by parsing certs.txt.

board/MynaPlayer odyssey: create initial empty ext4 filesystem for storing rauc slot status, and add this to the full disk image.

Initial commit.