[SCSI] sas: clear parent->rphy in sas_rphy_delete

We need to clear the backpointer on rphy removal, else we'll run into
problems with host removal after a device has been hot unplugged.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
diff --git a/drivers/scsi/scsi_transport_sas.c b/drivers/scsi/scsi_transport_sas.c
index edabbd0..357b52f 100644
--- a/drivers/scsi/scsi_transport_sas.c
+++ b/drivers/scsi/scsi_transport_sas.c
@@ -697,6 +697,8 @@
 	list_del(&rphy->list);
 	spin_unlock(&sas_host->lock);
 
+	parent->rphy = NULL;
+
 	put_device(&parent->dev);
 }
 EXPORT_SYMBOL(sas_rphy_delete);