[LEDE-DEV] RFC: removing support for old Atheros reference boards

[Felix Fietkau]

Hi all,

support code for some old ar71xx reference boards (e.g. AP83) carries
quite a bit of specific code that bloats images. I consider it highly
unlikely that anybody still actually uses this stuff, so I would like to
propose removing support for the following devices:
AP81
AP83
AP96
PB92
AP113

Note that for AP113 we have not built any images in years because of
flash layout limitations. The other devices are simply quite old.

Thoughts?

- Felix