staging: comedi: ni_pcidio: fix the cmd->start_arg use for TRIG_INT

This driver only a cmd->start_src of TRIG_NOW or TRIG_INT. The cmd->start_arg
is trivially validated for both sources to be 0. For a TRIG_INT source, the
cmd->start_arg is actually the valid trig_num that is passed to the async
(*inttrig) callback.

Refactor the (*inttrig) function so that the cmd->start_arg is used to check
the trig_num instead of the open coded value.
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>

drivers/staging/comedi/drivers/ni_pcidio.c

@@ -773,11 +773,13 @@ static int setup_mite_dma(struct comedi_device *dev, struct comedi_subdevice *s)
 }
 
 static int ni_pcidio_inttrig(struct comedi_device *dev,
-			     struct comedi_subdevice *s, unsigned int trignum)
+			     struct comedi_subdevice *s,
+			     unsigned int trig_num)
 {
 	struct nidio96_private *devpriv = dev->private;
+	struct comedi_cmd *cmd = &s->async->cmd;
 
-	if (trignum != 0)
+	if (trig_num != cmd->start_arg)
 		return -EINVAL;
 
 	writeb(devpriv->OpModeBits, devpriv->mite->daq_io_addr + OpMode);