fritz-tools: add fritz_tffs_nand_read tool

fritz-tools: add fritz_tffs_nand_read tool

A tool for reading the TFFS partitions (a name-value storage usually
found in AVM Fritz!Box based devices) on nand flash.

Copyright (c) 2018 Valentin Spreckels <Valentin.Spreckels@Informatik.Uni-Oldenburg.DE>

Based on the fritz_tffs_read tool:
    Copyright (c) 2015-2016 Martin Blumenstingl <martin.blumenstingl@googlemail.com>
and on the TFFS 2.0 kernel driver from AVM:
    Copyright (c) 2004-2007 AVM GmbH <fritzbox_info@avm.de>
and the TFFS 3.0 kernel driver from AVM:
    Copyright (C) 2004-2014 AVM GmbH <fritzbox_info@avm.de>
and the OpenWrt TFFS kernel driver:
    Copyright (c) 2013 John Crispin <blogic@openwrt.org>

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

Signed-off-by: Valentin Spreckels <Valentin.Spreckels@Informatik.Uni-Oldenburg.de>
Signed-off-by: Andy Binder <AndyBinder@gmx.de>