Remove Vertex Standard radio drivers

These drivers are known to be problematic in general, but also have
not been converted for use in chirp-next. This removes these from the
tree as there is no plan to modernize or fix them at this time.

If someone comes back to fix them in the future, they can be added
back. Since they're only usable in/by chirp-legacy there's really no
need to keep them alive in the main tree. Note that this will remove
them from the supported radios list.

Author: kk7ds