wifi: mac80211: move radar detect work to sdata

At some point we thought perhaps this could be per link, but
really that didn't happen, and it's confusing. Radar detection
still uses the deflink to allocate the channel, but the work
need not be there. Move it back.

Reviewed-by: Miriam Rachel Korenblit <miriam.rachel.korenblit@intel.com>
Link: https://msgid.link/20240506211311.43bd82c6da04.Ib39bec3aa198d137385f081e7e1910dcbde3aa1b@changeid


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