dt-bindings: net: wireless: ath10k: add ieee80211-freq-limit property

This is an existing optional property that ieee80211.yaml/cfg80211
provides. It's useful to further restrict supported frequencies
for a specified device through device-tree.

For testing the addition, I added the ieee80211-freq-limit
property with values from an OpenMesh A62 device. This is
because the OpenMesh A62 has "special filters in front of
the RX+TX paths to the 5GHz PHYs. These filtered channel
can in theory still be used by the hardware but the signal
strength is reduced so much that it makes no sense."

The driver supported this since ~2018 by
commit 34d5629d ("ath10k: limit available channels via DT ieee80211-freq-limit")

Link: https://git.openwrt.org/?p=openwrt/openwrt.git;a=commit;h=e3b8ae2b09e137ce2eae33551923daf302293a0c


Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/c33c928b7c6c9bb4e7abe84eb8df9f440add275b.1686486464.git.chunkeey@gmail.com