mac80211: use sdata pointer for scan interface

Since we now use sdata pointers most of the time, using a netdev
pointer here is somewhat artificial, use an sdata pointer instead.
Replace a netdev-prefix in a few messages by a wiphy-prefix.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 7dc0631..6df4a2e 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -551,7 +551,7 @@
 		synchronize_rcu();
 		skb_queue_purge(&sdata->u.sta.skb_queue);
 
-		if (local->scan_dev == sdata->dev) {
+		if (local->scan_sdata == sdata) {
 			if (!local->ops->hw_scan) {
 				local->sta_sw_scanning = 0;
 				cancel_delayed_work(&local->scan_work);