pata_radisys: fix UDMA handling

Set correct bits to switch between UDMA2 and UDMA4.
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/pata_radisys.c

@@ -139,9 +139,9 @@ static void radisys_set_dmamode (struct ata_port *ap, struct ata_device *adev)
 		pci_read_config_byte(dev, 0x4A, &udma_mode);
 
 		if (adev->xfer_mode == XFER_UDMA_2)
-			udma_mode &= ~ (1 << adev->devno);
+			udma_mode &= ~(2 << (adev->devno * 4));
 		else /* UDMA 4 */
-			udma_mode |= (1 << adev->devno);
+			udma_mode |= (2 << (adev->devno * 4));
 
 		pci_write_config_byte(dev, 0x4A, udma_mode);