Bluetooth: Use NULL instead of integer for mgmt_device_connected param

Last param of mgmt_device_connected is of pointer type, so use NULL
instead of 0 for it. This fix following sparse warning:

CHECK   net/bluetooth/hci_event.c
net/bluetooth/hci_event.c:3262:74: warning: Using plain integer as NULL pointer
Signed-off-by: Szymon Janc <szymon@janc.net.pl>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

net/bluetooth/hci_event.c

@@ -3296,7 +3296,7 @@ static inline void hci_le_conn_complete_evt(struct hci_dev *hdev, struct sk_buff
 
 	if (!test_and_set_bit(HCI_CONN_MGMT_CONNECTED, &conn->flags))
 		mgmt_device_connected(hdev, &ev->bdaddr, conn->type,
-						conn->dst_type, 0, NULL, 0, 0);
+					conn->dst_type, 0, NULL, 0, NULL);
 
 	conn->sec_level = BT_SECURITY_LOW;
 	conn->handle = __le16_to_cpu(ev->handle);