staging: comedi: addi_apci_3xxx: boards do not have a timer

None of the boards supported by this driver have a timer. Remove
the unnecessary code.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Reviewed-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>