This fixes the UAF on __hci_acl_create_connection_sync caused by
connection abortion, it uses the same logic as to LE_LINK which uses
hci_cmd_sync_cancel to prevent the callback to run if the connection is
abort prematurely.

Reported-by: syzbot+3f0a39be7a2035700868@syzkaller.appspotmail.com
Fixes: 45340097 ("Bluetooth: hci_conn: Only do ACL connections sequentially")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>