cmd640: fix kernel oops in test_irq() method

commit a9ddabc5 upstream.

When implementing the test_iqr() method, I forgot that this driver is not an
ordinary PCI driver and also needs to support VLB variant of the chip. Moreover,
'hwif->dev' should be NULL, potentially causing oops in pci_read_config_byte().
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/ide/cmd640.c

@@ -632,12 +632,10 @@ static void cmd640_init_dev(ide_drive_t *drive)
 
 static int cmd640_test_irq(ide_hwif_t *hwif)
 {
-	struct pci_dev *dev	= to_pci_dev(hwif->dev);
 	int irq_reg		= hwif->channel ? ARTTIM23 : CFR;
-	u8  irq_stat, irq_mask	= hwif->channel ? ARTTIM23_IDE23INTR :
+	u8  irq_mask		= hwif->channel ? ARTTIM23_IDE23INTR :
 						  CFR_IDE01INTR;
-
-	pci_read_config_byte(dev, irq_reg, &irq_stat);
+	u8  irq_stat		= get_cmd640_reg(irq_reg);
 
 	return (irq_stat & irq_mask) ? 1 : 0;
 }