staging: comedi: das16: remove a duplicate condition

We checked that "it->options[3]" was non-zero on the line before so
there is no need to check again.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-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/das16.c

@@ -1032,8 +1032,7 @@ static int das16_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 
 	/*  check that clock setting is valid */
 	if (it->options[3]) {
-		if (it->options[3] != 0 &&
-		    it->options[3] != 1 && it->options[3] != 10) {
+		if (it->options[3] != 1 && it->options[3] != 10) {
 			dev_err(dev->class_dev,
 				"Invalid option. Master clock must be set to 1 or 10 (MHz)\n");
 			return -EINVAL;