The core device has an attach address method as the root of the tree
which calls out to the sim API. But it doesn't have a corresponding
detach method which means we just crash if anything tries to detach
itself from the core. In practice, the m68hc11 is the only model
that actually tries to detach itself on the fly, so no one noticed
earlier.
With this in place, we can delete the existing detach code from the
m68hc11 model since it defaults to "passthru" callback which will in
turn call the dv-core detach, and they have the same behavior -- call
the sim core API to detach from the address space.
Bug: https://sourceware.org/PR25211
09d236daec