Staging: comedi: unlock on error in usbdux_ao_inttrig()

If we had an invalid trignum (anything other than zero is invalid) then
we returned without unlocking.  I've modified this function to just have
one return point.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/comedi/drivers/usbduxsigma.c

@@ -1523,15 +1523,17 @@ static int usbdux_ao_inttrig(struct comedi_device *dev,
 		return -EFAULT;
 
 	down(&this_usbduxsub->sem);
+
 	if (!(this_usbduxsub->probed)) {
-		up(&this_usbduxsub->sem);
-		return -ENODEV;
+		ret = -ENODEV;
+		goto out;
 	}
 	if (trignum != 0) {
 		dev_err(&this_usbduxsub->interface->dev,
 			"comedi%d: usbdux_ao_inttrig: invalid trignum\n",
 			dev->minor);
-		return -EINVAL;
+		ret = -EINVAL;
+		goto out;
 	}
 	if (!(this_usbduxsub->ao_cmd_running)) {
 		this_usbduxsub->ao_cmd_running = 1;
@@ -1541,17 +1543,18 @@ static int usbdux_ao_inttrig(struct comedi_device *dev,
 				"comedi%d: usbdux_ao_inttrig: submitURB: "
 				"err=%d\n", dev->minor, ret);
 			this_usbduxsub->ao_cmd_running = 0;
-			up(&this_usbduxsub->sem);
-			return ret;
+			goto out;
 		}
 		s->async->inttrig = NULL;
 	} else {
 		dev_err(&this_usbduxsub->interface->dev,
 			"comedi%d: ao_inttrig but acqu is already running.\n",
 			dev->minor);
 	}
+	ret = 1;
+out:
 	up(&this_usbduxsub->sem);
-	return 1;
+	return ret;
 }
 
 static int usbdux_ao_cmdtest(struct comedi_device *dev,