Bluetooth: Fix clearing of dev_class when powering down

We should assume a value of 0 for the device class when powered off.
The appropriate place to do this is in hci_dev_do_close().

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/hci_core.c

@@ -795,6 +795,7 @@ static int hci_dev_do_close(struct hci_dev *hdev)
 	hdev->flags = 0;
 
 	memset(hdev->eir, 0, sizeof(hdev->eir));
+	memset(hdev->dev_class, 0, sizeof(hdev->dev_class));
 
 	hci_req_unlock(hdev);