Bluetooth: Ignore incoming data after initiating disconnection

Bluetooth: Ignore incoming data after initiating disconnection

When hci_chan_del is called the disconnection routines get scheduled
through a workqueue. If there's any incoming ACL data before the
routines get executed there's a chance that a new hci_chan is created
and the disconnection never happens. This patch adds a new hci_conn flag
to indicate that we're in the process of driving the connection down. We
set the flag in hci_chan_del and check for it in hci_chan_create so that
no new channels are created for the same connection.

Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>