Bluetooth: separate CIS_LINK and BIS_LINK link types

Use separate link type id for unicast and broadcast ISO connections.
These connection types are handled with separate HCI commands, socket
API is different, and hci_conn has union fields that are different in
the two cases, so they shall not be mixed up.

Currently in most places it is attempted to distinguish ucast by
bacmp(&c->dst, BDADDR_ANY) but it is wrong as dst is set for bcast sink
hci_conn in iso_conn_ready(). Additionally checking sync_handle might be
OK, but depends on details of bcast conn configuration flow.

To avoid complicating it, use separate link types.

Fixes: f764a6c2 ("Bluetooth: ISO: Add broadcast support")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>