staging: comedi: das800: 'dev->subdevices + 0' is already known

There is no need to calculate the subdevice for the call to
das800_cancel. The variable 's' in this function is set to the
'dev->read_subdev' which is the same as 'dev->subdevices + 0'.
Signed-off-by: NH Hartley Sweeten <hsweeten@visionengravers.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/das800.c

@@ -435,7 +435,7 @@ static irqreturn_t das800_interrupt(int irq, void *d)
 	if (fifo_overflow) {
 		spin_unlock_irqrestore(&dev->spinlock, irq_flags);
 		comedi_error(dev, "DAS800 FIFO overflow");
-		das800_cancel(dev, dev->subdevices + 0);
+		das800_cancel(dev, s);
 		async->events |= COMEDI_CB_ERROR | COMEDI_CB_EOA;
 		comedi_event(dev, s);
 		async->events = 0;