wifi: mac80211: collect some CSA data into sub-structs

Collect the CSA data in ieee80211_link_data_managed and
ieee80211_link_data into a csa sub-struct to clean up a
bit and make adding new things more obvious.

Reviewed-by: Miriam Rachel Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240506215543.29f954b1f576.I9a683a9647c33d4dd3011aade6677982428c1082@changeid


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