mac80211: Restructure ieee80211_tx_info->control to gain free space along tx-path

[Thomas Huehn]

In order to enable new annotations per data packet along the max80211 tx-path,
(e.g. upcoming Transmit Power Control (TPC) per packet) this patch-serie does:

- fix the ieee80211_tx_info->control usage in driver mac80211_hwsim
- remove control.sta from ieee80211_tx_info and adapt all affected drivers


Greetings Thomas                                                                                                                                                                                                                        

---
CC list is a reduced "get_maintainer.pl", focuses on mailing lists - suggested
by J. Berg