[LEDE-DEV] Convert ar71xx to devicetree

[p.wassi at gmx.at]

> > how would that be confusing ? i would argue the exact opposite
> Because suddenly there are two targets and you have to look up which
> device is supported by which target.

We'd just fill ath79 with supported targets and can discuss, whether these
supported devices should then disappear in ar71xx?
(As previously said, I'm aware removing devices is not that user friendly,
but would make a clear transition between non-DT and DT)

For DT and non-DT in the same kernel:
I'm currently using a different kernel config for RAW_APPENDED_DTB
and CMDLINE_FROM_DTB and also disabled all the mach-*.c files.
Beginning with a new target, we could start with a *clean* arch directory.

Best regards,
P. Wassi