There are only a few places where the returned rix is used:
- linuxkpi - logging
- bwi/bwn - used for finding a fallback rate to choose, which honestly should be returned by the ratectl API
- iwm - building the rateset to program into firmware
Everyone else uses the dot11rate value in ni->ni_txnode.
This is a precursor for VHT and later rate support; where currently
there aren't rate tables in ieee80211_phy.c for VHT and later
rates.
Although it's likely doable to add tables for VHT, 11ax and MU-OFDMA
(HE) rates are sufficiently larger/different to just not fit in the
current scheme without more refactoring.