staging: comedi: dt2814: use dev->read_subdev

Use the dev->read_subdev that was setup in the device attach instead
of accessing the dev->subdevices array directly.
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/dt2814.c

@@ -197,7 +197,7 @@ static irqreturn_t dt2814_interrupt(int irq, void *d)
 	int lo, hi;
 	struct comedi_device *dev = d;
 	struct dt2814_private *devpriv = dev->private;
-	struct comedi_subdevice *s;
+	struct comedi_subdevice *s = dev->read_subdev;
 	int data;
 
 	if (!dev->attached) {
@@ -205,8 +205,6 @@ static irqreturn_t dt2814_interrupt(int irq, void *d)
 		return IRQ_HANDLED;
 	}
 
-	s = &dev->subdevices[0];
-
 	hi = inb(dev->iobase + DT2814_DATA);
 	lo = inb(dev->iobase + DT2814_DATA);