wifi: mac80211: add EHT 320 MHz support for mesh

Currently, ieee80211_ie_build_he_oper() lacks support for 320 MHz handling
(already noted as a TODO). This is because 320 MHz is not included in
IEEE 802.11-ax. However, IEEE 802.11-be introduces 320 MHz support and if
the chandef indicates a 320 MHz bandwidth and is used directly as it is, it
will result in an incorrect HE Operation Information Element.

In order to support EHT 320 MHz, HE Operation Element should indicate
bandwidth as 160 MHz only. In EHT Operation IE, the correct bandwidth will
be present. Devices capable of EHT can parse EHT Information Element and
connect in 320 MHz and other HE capable devices can parse HE and can
connect in 160 MHz.

Add support to downgrade the bandwidth in ieee80211_ie_build_he_oper()
during 320 MHz operation and advertise it.

Signed-off-by: Sathishkumar Muruganandam <quic_murugana@quicinc.com>
Signed-off-by: Aditya Kumar Singh <quic_adisi@quicinc.com>
Link: https://patch.msgid.link/20241119-mesh_320mhz_support-v1-1-f9463338d584@quicinc.com


Signed-off-by: Johannes Berg <johannes.berg@intel.com>