[LEDE-DEV] ar71xx: add tp-link 841nd-v9-vn board - 8mbit flash isp oem variant

[Luke McKee]

https://github.com/openwrt/openwrt/pull/29
https://github.com/openwrt/openwrt/pull/29/commits/84c616f66390230a2938f8db691e8093f1669ec2

Please see the commit message or the forum. This has been run-tested
on the new hardware which is basically the same as a v9 board just
with the larger flash size
https://forum.openwrt.org/viewtopic.php?id=65786
Users can install factory.bin's via tp-link firmware, or use
sysupgrade - both tested successfully. As you can see from the factory
rom extracted via uboot, it really does have different HWID's used by
tp-link to distinguish the OEM order for larger flash size. They add a
1 at the end of the HWID to denote that.

If a user bricks a tp-link 841nd v9 , the factory bootloader has a
tftp recovery method as demonstrated. In any case -v9-vn firmware will
not install on -v9 firwmare and visa versa. There isn't much need for
pico''s patched u-boot I think, except for the frills of a web-browser
to upgrade the flash and loosing your Ethernet mac address.

https://www.youtube.com/watch?v=0k1sxwX5pMk