[Bluetooth] Add open and close callbacks for HID device

The open and close callbacks for the HID device are not optional, but
for the Bluetooth HID report mode support it is enough to add empty
dummy callbacks.
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/hidp/core.c

@@ -670,6 +670,15 @@ static inline void hidp_setup_input(struct hidp_session *session, struct hidp_co
 	input_register_device(input);
 }
 
+static int hidp_open(struct hid_device *hid)
+{
+	return 0;
+}
+
+static void hidp_close(struct hid_device *hid)
+{
+}
+
 static inline void hidp_setup_hid(struct hidp_session *session, struct hidp_connadd_req *req)
 {
 	struct hid_device *hid = session->hid;
@@ -694,6 +703,9 @@ static inline void hidp_setup_hid(struct hidp_session *session, struct hidp_conn
 
 	hid->dev = hidp_get_device(session);
 
+	hid->hid_open  = hidp_open;
+	hid->hid_close = hidp_close;
+
 	hid->hidinput_input_event = hidp_hidinput_event;
 
 	list_for_each_entry(report, &hid->report_enum[HID_INPUT_REPORT].report_list, list)