Bluetooth: Fix SCO state handling for incoming connections

When the remote device supports only SCO connections, on receipt of
the HCI_EV_CONN_COMPLETE event packet, the connect state is changed to
BT_CONNECTED, but the socket state is not updated. Hence, the connect()
call times out even though the SCO connection has been successfully
established.

Based on a report by Jaikumar Ganesh <jaikumar@google.com>

Signed-off-by: Marcel Holtmann <marcel@holtmann.org>