Previously, every device package would package its own /etc/deviceinfo
file, generating a conflict with every other device package. In a
previous commit we have moved the path to /usr/share/deviceinfo, but
we still want to install a sample "/etc/deviceinfo" file to guide
users on how to use the new features. This has the additional benefit
that there is only one of those files in the whole distro. However,
there is no dependency ordering between the device packages and
devicepkg-utils, so there's no warranty of which will be installed
first. Therefore, to avoid a conflict on most likely every user
upgrade, we use postmarketos-mvcfg.
