Revert "mac80211: clear sta.drv_priv on reconfiguration"

This reverts commit f785d83a.

This was provoking WARNINGs from the iwlegacy drivers.
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

net/mac80211/util.c

@@ -1038,7 +1038,6 @@ int ieee80211_reconfig(struct ieee80211_local *local)
 					     struct ieee80211_sub_if_data,
 					     u.ap);
 
-			memset(&sta->sta.drv_priv, 0, hw->sta_data_size);
 			WARN_ON(drv_sta_add(local, sdata, &sta->sta));
 		}
 	}