staging: comedi: cb_pcidas: cleanup cb_pcidas_ao_fifo_winsn()

Create local variables for the channel and range in order to
cleanup to mask/set of the ao_control_bits.

Remove the extra space in all the comments.

Return the number of data parameters used (insn->n) to indicate
success instead of the open coded '1'.

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>