Bluetooth: mgmt: Fix device_connected sending order.  The mgmt_ev_device_connected signal must be sent before any event indications happen for sockets associated with the connection. Otherwise e.g. device authorization for the sockets will fail with ENOTCONN as user space things that there is no baseband link.  This patch fixes the issue by ensuring that the device_connected event is sent (if it hasn't been so already) as soon as the first ACL data packet arrives from the remote device.