o don't pre-assign key index to the global key table entries so device
has a chance to decide what to use
o make ieee80211_crypto_newkey take the desired flags as an argument
instead of wacking the key structure directly; this eliminates a
bunch of code warts
o add a new flag IEEE80211_KEY_GROUP to indicate a key is a WPA Group
key so devices don't need to guess (temporarily add this flag in the
ioctl code until we can get wpa_supplicant+hostapd updated)
o shuffle IEEE80211_KEY_* bits to move flags used internally to the high
nibble of the flags word
Reviewed by: Tai-hwa Liang