mac80211: avoid NULL ptr deref when using WEP

"mac80211: move control.hw_key assignment" changed an if-else into two
separate if statments, but the if-else is needed to prevent
dereferencing a null info->control.hw_key.  This fixes avoids a lock-up
during association on my machine when using WEP.

Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/mac80211/wep.c b/net/mac80211/wep.c
index 0a4c641..5d745f2 100644
--- a/net/mac80211/wep.c
+++ b/net/mac80211/wep.c
@@ -310,9 +310,8 @@
 					  tx->key->conf.keylen,
 					  tx->key->conf.keyidx))
 			return -1;
-	}
-
-	if (info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) {
+	} else if (info->control.hw_key->flags &
+			IEEE80211_KEY_FLAG_GENERATE_IV) {
 		if (!ieee80211_wep_add_iv(tx->local, skb,
 					  tx->key->conf.keylen,
 					  tx->key->conf.keyidx))