rtwn: add rtwn_ctl_vhtrate(), some cleanups

[adrian]

Summary

• Add a placeholder rtwn_ctl_vhtrate() which returns the dot11rate control rate to use for the given VHT rate index. Since net80211 currently doesn't have any VHT PHY tables, there's no mapping for us to leverage so just return OFDM 12M for now.

• Use the new macro to convert rate index to MCS rate

• Add a printf() in rate2ridx if it's passed a HT/VHT rate.

[fuz]

That stub looks sane.

[bz]

sys/dev/rtwn/if_rtwn_ridx.h

100

return takes ()

[bz]

otherwise I am fine with it if you are.

sys/dev/rtwn/if_rtwn_ridx.h

116

and while here you could add them here too and the file might be neat and tidy ;-)

129

Here too.

[adrian]

address feedback from bz