o Slightly change KBADDKBD and KBRELKBD ioctl() interface. Instead of passing
keyboard index pass keyboard_info_t structure with populated 'kb_unit' and
'kb_name' fields. Keyboard index is not very user-friendly and is not very
easy to obtain. Keyboard driver name and unit, on the other hand, is much
more user friendly and known almost all the time;
o Move definition of keyboard_info_t structure up;
o Teach kbdcontrol(1) how to attach/detach keyboards to/from the keyboard
multiplexor;
o Update kbdcontrol(1) man page and document new functionality.
To attach/detach keyboard to/from keyboard multiplexor one needs to use
keyboard device name (i.e. ukbd0).
MFC after: 1 week
d2de93780c