Only assign hdev->wakeup if the serial port supports wakeup. Otherwise
it will fall back to the hci_uart_wakeup or the behavior that can be
overridden before calling the hci_uart_register_device().
Signed-off-by: NZhengping Jiang <jiangzp@google.com>
Signed-off-by: NLuiz Augusto von Dentz <luiz.von.dentz@intel.com>