Bluetooth: Ignore hci_unregister_dev return value

Make all bluetooth drivers ignore the return value of hci_unregister_dev as it
always returns 0. In the next step, hci_unregister_dev can be modified to return
void.
Some of the drivers already ignore the return value (including btusb), hence,
this will increase consitency in the bluetooth drivers.

Signed-off-by: David Herrmann <dh.herrmann@googlemail.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

drivers/bluetooth/dtl1_cs.c

@@ -551,9 +551,7 @@ static int dtl1_close(dtl1_info_t *info)
 
 	spin_unlock_irqrestore(&(info->lock), flags);
 
-	if (hci_unregister_dev(hdev) < 0)
-		BT_ERR("Can't unregister HCI device %s", hdev->name);
-
+	hci_unregister_dev(hdev);
 	hci_free_dev(hdev);
 
 	return 0;