Bluetooth: Add wait_queue to wait ack of all sent packets

To guarantee that all packets we sent were received we need to wait for
theirs ack before shutdown the socket.

Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>
Reviewed-by: João Paulo Rechi Vita <jprvita@profusion.mobi>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>