The XBee cellular support is at the moment only in modemmanager's git
repository (master branch).
Also remove one Telit patch from the bbappend because it's already
included in the git repo.
https://jira.digi.com/browse/DEL-3841
Signed-off-by: Javier Viguera <javier.viguera@digi.com>
Javier Viguera