wifi: iwlwifi: mvm: add support for post_channel_switch in MLD mode

Adjust the existing iwl_mvm_post_channel_switch()
to the new MLD API and use it in the new MLD ieee80211_ops

Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230328104948.fa3992f7dfd2.Ie298a9b1522e956d7b699f0432795548bc6e47f9@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>