mac80211: Fix quality reporting for wireless stats

Since "mac80211/cfg80211: move iwrange handler to cfg80211", the
results for link quality from "iwlist scan" and "iwconfig" commands
have been very different. The results are now consistent.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Reported- and tested-by: Larry Finger <larry.finger@lwfinger.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>