pata_ixp4xx_cf: fix oops on detach

pata_ixp4xx_cf dodged dont-clear-drvdata-in-LLD bombing run as it used
platform_set_drvdata() instead of dev_set_drvdata().  This causes OOPS
on devres host release.  Kill it.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/ata/pata_ixp4xx_cf.c b/drivers/ata/pata_ixp4xx_cf.c
index 9a0523b..bbcc9e7 100644
--- a/drivers/ata/pata_ixp4xx_cf.c
+++ b/drivers/ata/pata_ixp4xx_cf.c
@@ -232,7 +232,6 @@
 	struct ata_host *host = platform_get_drvdata(dev);
 
 	ata_host_detach(host);
-	platform_set_drvdata(dev, NULL);
 
 	return 0;
 }