staging: comedi: cb_pcidas: fix cb_pcidas_ao_nofifo_insn_write()

The comedi core expects (*insn_write) functions to write insn->n
data values to the hardware. Fix this function to work like the
core expects.

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>