This change currently (partially) duplicates AC1 freqbands as AC2
as they are not fully overlapping.
It then adds the 11ac netband to the "etsi" domain including
"indoor" and "dfs" flags, which we can deal with, as well as
(I hope) appropriate (round down) maxpower values.
I left comments for the actual frequency bands as we do use the
centerfreq for the first/last (chansep sized) channel in the
freqband and their "id" name, which can be confusing.
I keep wondering if we should set the HT20 and HT40 flags on the
freqbands like we do for A already rather than adding them to the
indivdual netband band statements.
The current rule, as I understand it, is that you want
1x A, 1x N (HT), and 1x AC (VHT) flags on a band and no duplicate
VHT, e.g., VHT40+VHT80 as that would lead to possible duplicates.
The same logic needs to be in at least the kernel for getflags_5ghz()
if not also being matched in ifconfig(8).
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