staging: comedi: pcl711: use comedi_fc helpers to validate timer arg

Use the comedi_fc helper cfc_check_trigger_arg_is() to validate the
trigger argument when the source is TRIG_TIMER.

All the arguments are unsigned int, change the local variable to an
unsigned int and rename it for aesthetic reasons.
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/pcl711.c

@@ -295,8 +295,8 @@ static int pcl711_ai_cmdtest(struct comedi_device *dev,
 			     struct comedi_subdevice *s, struct comedi_cmd *cmd)
 {
 	struct pcl711_private *devpriv = dev->private;
-	int tmp;
 	int err = 0;
+	unsigned int arg;
 
 	/* Step 1 : check if triggers are trivially valid */
 
@@ -344,14 +344,12 @@ static int pcl711_ai_cmdtest(struct comedi_device *dev,
 	/* step 4 */
 
 	if (cmd->scan_begin_src == TRIG_TIMER) {
-		tmp = cmd->scan_begin_arg;
+		arg = cmd->scan_begin_arg;
 		i8253_cascade_ns_to_timer(I8254_OSC_BASE_2MHZ,
 					  &devpriv->divisor1,
 					  &devpriv->divisor2,
-					  &cmd->scan_begin_arg,
-					  cmd->flags);
-		if (tmp != cmd->scan_begin_arg)
-			err++;
+					  &arg, cmd->flags);
+		err |= cfc_check_trigger_arg_is(&cmd->scan_begin_arg, arg);
 	}
 
 	if (err)