Bluetooth: AMP: Add handle to hci_chan structure

hci_chan will be identified by handle used in logical link creation
process. This handle is used in AMP ACL-U packet handle field.

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>