staging: comedi: me4000: validate cmd->stop_arg in step 3 of (*do_cmdtest)

The async command arguments are supposed to be trivially validated in step 3
of the (*do_cmdtest). Fix the validation of the stop_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/me4000.c

@@ -923,6 +923,11 @@ static int me4000_ai_do_cmd_test(struct comedi_device *dev,
 		err |= -EINVAL;
 	}
 
+	if (cmd->stop_src == TRIG_COUNT)
+		err |= cfc_check_trigger_arg_min(&cmd->stop_arg, 1);
+	else	/* TRIG_NONE */
+		err |= cfc_check_trigger_arg_is(&cmd->stop_arg, 0);
+
 	if (err)
 		return 3;
 
@@ -1029,13 +1034,6 @@ static int me4000_ai_do_cmd_test(struct comedi_device *dev,
 			err++;
 		}
 	}
-	if (cmd->stop_src == TRIG_COUNT) {
-		if (cmd->stop_arg == 0) {
-			dev_err(dev->class_dev, "Invalid stop arg\n");
-			cmd->stop_arg = 1;
-			err++;
-		}
-	}
 	if (cmd->scan_end_src == TRIG_COUNT) {
 		if (cmd->scan_end_arg == 0) {
 			dev_err(dev->class_dev, "Invalid scan end arg\n");