mac80211: calculate wstats_flags on the fly

Just to make wext.c more self-contained.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --cc net/mac80211/ieee80211_i.h
Simple merge

diff --cc net/mac80211/main.c
Simple merge

diff --cc net/mac80211/wext.c
Simple merge