staging: comedi: addi_apci_3xxx: 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.

For aesthetics, rename the local variable 'tmp' to 'arg'.
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/addi_apci_3xxx.c

@@ -533,7 +533,7 @@ static int apci3xxx_ai_cmdtest(struct comedi_device *dev,
 {
 	const struct apci3xxx_boardinfo *board = comedi_board(dev);
 	int err = 0;
-	unsigned int tmp;
+	unsigned int arg;
 
 	/* Step 1 : check if triggers are trivially valid */
 
@@ -573,11 +573,9 @@ static int apci3xxx_ai_cmdtest(struct comedi_device *dev,
 
 	/* step 4: fix up any arguments */
 
-	tmp = cmd->convert_arg;
-	err |= apci3xxx_ai_ns_to_timer(dev, &cmd->convert_arg,
-				       cmd->flags & TRIG_ROUND_MASK);
-	if (tmp != cmd->convert_arg)
-		err |= -EINVAL;
+	arg = cmd->convert_arg;
+	err |= apci3xxx_ai_ns_to_timer(dev, &arg, cmd->flags & TRIG_ROUND_MASK);
+	err |= cfc_check_trigger_arg_is(&cmd->convert_arg, arg);
 
 	if (err)
 		return 4;