This should get rid of "atkbd.c: Suprious NAK on isa0060/serio0"
messages caused by broken MUX implementation. The box does not
have external PS/2 ports and, according to documentation,
automatically disables touchpad when an external mouse is plugged
into a port replicator, so MUX mode would not work anyway.
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>