With commit 385200443554 ("babeld: add add_interface function") babeld
has a new ubus function allowing to dynamically add an interface.

Before the add_interface function, we were required to reload babeld.
The reload influenced the babeld routing. However, the remove part is
still missing and will be added at a later stage.

Signed-off-by: Nick Hainke <vincent@systemli.org>