upgrade-from.d : remove unused parameters

$BASEDIR, $ROLE, $TO, $FROM were parmeters declared in the upgrade file but
actually unused.
$TDIR is now replaced by the $dir value passed when the upgrade file is run.
upgrade-from.d: remove uselss export DEBIAN_FRONTEND

Since export DEBIAN_FRONTEND is set on the common script and common script
is sourced in the upgrade file, there was no use to export it again.
Merge pull request #13 from Spredzy/remove_unused_parameters_in_upgrade_file

Remove unused parameters in upgrade file