staging: comedi: pcl711: use 8253.h helper to set the timers

To better document the code, use the i8254_load() helper to set the
timers instead of doing the outb() instructions.

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>