Added Support for TP-Link WR843ND

[Ranlvor]

Tests done to verify that this worked as intended:

• checked plattform_info image_name
• checked primary_mac
• does appear in ffmap-d3
• does mesh
• does fastd-VPN

[rotanid]

reading your Pull Request i noticed, that there are some models like your 843 and 842 and 1043 which have a "N/ND" in their description/comment, although there are only the ND ones available on TP-Links website and everywhere else.
if no one objects, i can prepare a pull request which changes this to "ND" only.

[Ranlvor]

This N/ND-Stuff is weird. For example my code says

tl-wr843nd-v1,tp-link-tl-wr843n-nd-v1

because the OpenWRT-Image is called nd-v1 while the autoupdater expects an image to be called n-nd-v1 according to the output of

lua -e 'print(require("platform_info").get_image_name())'

To your proposed Pull Request: The software doen't realy seem to care about the N/ND-difference and so do I.

[rotanid]

this is cosmetic, so i don't insist on changig that, if @NeoRaider voices reasons not to do it