staging: comedi: das_08: remove the cached 8254 'mode'

The driver initially sets all the cached 'mode' values for the
8254 timers to (I8254_MODE0 | I8254_BINARY). It then sets the
timers to that 'mode'. Configuring the counters with the comedi
INSN_CONFIG_SET_COUNTER_MODE updates the 'mode' and then sets
the timers to the 'mode'. The cached value is never read or
used other than for storage.

Just remove the 'mode' usage as it serves no purpose.

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