Fixed Borg toggling broadcast mode

this is my first pull request so if i missed something let me know.
This fixes the borg toggling broadcast mode bug in <a href="hhttps://github.com/Baystation12/Baystation12/issues/4441">#4441</a>
the /obj/item/device/radio/borg/Topic(href, href_list) probably could be coded a little neater but it works.