staging: comedi: amplc_pci224: always cascade the 8254 timers

The 8254 timers are only used in this driver to generate the analog
output pacer. To simplify the driver, always cascade the timers.

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