- Add detach support to the driver so that you can kldunload the module.
Note that currently rc_detach() fails to detach a unit if any of its
child devices are open, thus a kldunload will fail if any of the tty
devices are currently open.
- sys/i386/isa/ic/cd180.h was moved to sys/dev/ic/cd180.h as part of
this change.
Requested by: rwatson
Tested by: rwatson
