wifi: mac80211: fix AP chandef capturing in CSA

wifi: mac80211: fix AP chandef capturing in CSA

When the CSA is announced with only HT elements, the AP
chandef isn't captured correctly, leading to crashes in
the later code that checks for TPE changes during CSA.

Capture the AP chandef correctly in both cases to fix
this.

Reported-by: Jouni Malinen <j@w1.fi>
Fixes: 4540568136fe ("wifi: mac80211: handle TPE element during CSA")
Link: https://patch.msgid.link/20240709160851.47805f24624d.I024091f701447f7921e93bb23b46e01c2f46347d@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>