Add disconnect callback function in btusb_disconnect which is reserved
for vendor specific usage before deregister hci in btusb_disconnect.

Signed-off-by: Chris Lu <chris.lu@mediatek.com>
---
 drivers/bluetooth/btusb.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
index 6cf1729a8225..dfc42bdc8aaf 100644
--- a/drivers/bluetooth/btusb.c
+++ b/drivers/bluetooth/btusb.c
@@ -846,6 +846,7 @@ struct btusb_data {
 
 	int (*suspend)(struct hci_dev *hdev);
 	int (*resume)(struct hci_dev *hdev);
+	int (*disconnect)(struct hci_dev *hdev);
 
 	int oob_wake_irq;   /* irq for out-of-band wake-on-bt */
 	unsigned cmd_timeout_cnt;
@@ -4011,6 +4012,9 @@ static void btusb_disconnect(struct usb_interface *intf)
 	if (data->diag)
 		usb_set_intfdata(data->diag, NULL);
 
+	if (data->disconnect)
+		data->disconnect(hdev);
+
 	hci_unregister_dev(hdev);
 
 	if (intf == data->intf) {
-- 
2.18.0