landing key mgmt cleanups ; please update -head and test

hi!

I'm starting to land crypto key management cleanups. I'm trying to get
rid of any/all of the
last remnants of directly poking at net80211 key entries / doing
pointer arithmetic to figure
out what kind of key it is and what key contents to program in.

I want to get this all done before I tackle adding the placeholder
keys for MFP/802.11w.

If you're using if_run / if_rum (older USB devices) and/or if_iwx then
please update to -head and let me know. Doubly so if you're using
TKIP.

I'll push the other cleanups into -head over the next few days.

Thanks!



-adrian