staging: comedi: amplc_pc236: check bus type in detach routine

When detaching the device in pc236_detach() mirror the bus type checks
performed by pc236_attach().  The existing tests are safe but rely on
dev->iobase being 0 when comedi_to_pci_dev(dev) is NULL.

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/comedi/drivers/amplc_pc236.c

@@ -580,8 +580,8 @@ static int __devinit pc236_attach_pci(struct comedi_device *dev,
 
 static void pc236_detach(struct comedi_device *dev)
 {
+	const struct pc236_board *thisboard = comedi_board(dev);
 	struct pc236_private *devpriv = dev->private;
-	struct pci_dev *pcidev = comedi_to_pci_dev(dev);
 
 	if (devpriv)
 		pc236_intr_disable(dev);
@@ -589,13 +589,16 @@ static void pc236_detach(struct comedi_device *dev)
 		free_irq(dev->irq, dev);
 	if (dev->subdevices)
 		subdev_8255_cleanup(dev, dev->subdevices + 0);
-	if (pcidev) {
-		if (dev->iobase)
-			comedi_pci_disable(pcidev);
-		pci_dev_put(pcidev);
-	} else {
+	if (is_isa_board(thisboard)) {
 		if (dev->iobase)
 			release_region(dev->iobase, PC236_IO_SIZE);
+	} else if (is_pci_board(thisboard)) {
+		struct pci_dev *pcidev = comedi_to_pci_dev(dev);
+		if (pcidev) {
+			if (dev->iobase)
+				comedi_pci_disable(pcidev);
+			pci_dev_put(pcidev);
+		}
 	}
 }