libata: clear drvdata in ata_host_release(), take#2

Clearing drvdata in ->remove_one causes NULL pointer deference.  Clear
drvdata only in ata_host_release() after all resources are freed.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/ata/pata_cs5520.c

@@ -306,7 +306,6 @@ static void __devexit cs5520_remove_one(struct pci_dev *pdev)
 	struct ata_host *host = dev_get_drvdata(dev);
 
 	ata_host_detach(host);
-	dev_set_drvdata(dev, NULL);
 }
 
 /**