net80211: improve error checking in ieee80211_parse_{wpa,rsn}

[avos]

Summary

• Add few checks for group/pairwise ciphers in ieee80211_parse_{wpa,rsn}.
• Split error code and cipher value in wpa_cipher() / rsn_cipher(); current hack with (1 << 32) does not work - it's 1, not 0 (originally detected by CSA).
• Return IEEE80211_REASON_UNSUPP_RSN_IE_VERSION instead of IEEE80211_REASON_IE_INVALID when version field is not equal to RSN_VERSION.

Test Plan

Tested with wpi(4) / urtwn(4); no visible regressions.

[adrian]

looks good to me!