nl80211: Reduce the number of nlctrl name resolution calls

nl80211: Reduce the number of nlctrl name resolution calls

The number of nlctrl name resolution calls required to connect to a
WPA2-PSK AP is 12. And each nlctrl name resolution call spends 55 micro
seconds on a lower spec CPU like Intel Atom N270. Reduce the number of
nctrl name resolution calls from 12 to 1 by caching the results of nctrl
name resolution calls on int size memory to speed up the connection
process a little bit.

Signed-off-by: Masashi Honma <masashi.honma@gmail.com>