[net80211] handle hardware encryption offload in the receive path

[adrian]

Summary

• teach the crypto modules about receive offload - although I have to do some further reviewing in places where we /can't/ have an RX key
• teach the RX data path about receive offload encryption - check the flag, handle NULL key, do decap and checking as appropriate.

[avos]

sys/net80211/ieee80211_crypto.c

600 ↗

(On Diff #22232)

some hardware can pass h/w key index - does it needed here?

sys/net80211/ieee80211_sta.c

748 ↗

(On Diff #22232)

here too

[adrian]

sys/net80211/ieee80211_crypto.c

600 ↗

(On Diff #22232)

Sure, but if we get a hardware key but it strips the IV, we still can't really check anything. :(