mac80211: fix WARN_ON in the new work code

ieee80211_work_rx_mgmt currently enqueues various management frames, including deauth and disassoc frames, however the function ieee80211_work_rx_queued_mgmt does not handle these, as they should only occur if the AP is buggy. It does emit a WARN_ON when this happens though, and several users have reported such instances.
Fix the WARN_ON by not queueing such frames in the first place.

---

@@ -1022,8 +1022,6 @@ ieee80211_rx_result ieee80211_work_rx_mg
 		case IEEE80211_STYPE_PROBE_RESP:
 		case IEEE80211_STYPE_ASSOC_RESP:
 		case IEEE80211_STYPE_REASSOC_RESP:
-		case IEEE80211_STYPE_DEAUTH:
-		case IEEE80211_STYPE_DISASSOC:
 			skb_queue_tail(&local->work_skb_queue, skb);
 			ieee80211_queue_work(&local->hw, &local->work_work);
 			return RX_QUEUED;