staging: comedi: ni_at_a2150: remove subdevice pointer math

Convert the comedi_subdevice access from pointer math to array
access.

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/ni_at_a2150.c

@@ -832,7 +832,7 @@ static int a2150_attach(struct comedi_device *dev, struct comedi_devconfig *it)
 		return ret;
 
 	/* analog input subdevice */
-	s = dev->subdevices + 0;
+	s = &dev->subdevices[0];
 	dev->read_subdev = s;
 	s->type = COMEDI_SUBD_AI;
 	s->subdev_flags = SDF_READABLE | SDF_GROUND | SDF_OTHER | SDF_CMD_READ;