wifi: iwlwifi: mvm: check the right csa_active

When the firmware says that the channel switch is happening, we check
that we know about that switch by checking the csa_active bit.

Until now, we checked the bss_conf from the vif instead of taking the
bss_conf of the link.
Fix that.

Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230620125813.63f835a4f578.I0bb2a231e4da506b7c751dc23a428558f9ecfa75@changeid


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