staging: comedi: dt2814: 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/dt2814.c

@@ -128,7 +128,7 @@ static int dt2814_ai_cmdtest(struct comedi_device *dev,
 			     struct comedi_subdevice *s, struct comedi_cmd *cmd)
 {
 	int err = 0;
-	int tmp;
+	unsigned int arg;
 
 	/* Step 1 : check if triggers are trivially valid */
 
@@ -170,10 +170,9 @@ static int dt2814_ai_cmdtest(struct comedi_device *dev,
 
 	/* step 4: fix up any arguments */
 
-	tmp = cmd->scan_begin_arg;
-	dt2814_ns_to_timer(&cmd->scan_begin_arg, cmd->flags & TRIG_ROUND_MASK);
-	if (tmp != cmd->scan_begin_arg)
-		err++;
+	arg = cmd->scan_begin_arg;
+	dt2814_ns_to_timer(&arg, cmd->flags & TRIG_ROUND_MASK);
+	err |= cfc_check_trigger_arg_is(&cmd->scan_begin_arg, arg);
 
 	if (err)
 		return 4;