[PATCH wireless-next 0/7] wifi: mac80211: minor TX cleanups

Here are some cleanups around the TX control path / status / build_hdr
area. This is way less than I've been trying to do, but these all seem
obvious and actually overall reduce the amount of code.

The first one really is a bugfix, in a way, but for a bug that didn't
really matter much (really the only side effect was setting control
port flag for preauth frames).

johannes