staging: r8188eu: simplify err handling for unknown station

If we receive a disassoc message from an unknown station, we can drop this
message immediately. Reorder the code to make this clearer.

Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20221129205152.128172-6-martin@kaiser.cxSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/r8188eu/core/rtw_mlme_ext.c

@@ -1435,6 +1435,7 @@ static void OnDisassoc(struct adapter *padapter, struct recv_frame *precv_frame)
 	struct wifidirect_info *pwdinfo = &padapter->wdinfo;
 	struct sta_info *psta;
 	struct sta_priv *pstapriv = &padapter->stapriv;
+	u8 updated = 0;
 
 	if (memcmp(mgmt->bssid, get_my_bssid(&pmlmeinfo->network), ETH_ALEN))
 		return;
@@ -1453,19 +1454,18 @@ static void OnDisassoc(struct adapter *padapter, struct recv_frame *precv_frame)
 	}
 
 	psta = rtw_get_stainfo(pstapriv, mgmt->sa);
-	if (psta) {
-		u8 updated = 0;
-
-		spin_lock_bh(&pstapriv->asoc_list_lock);
-		if (!list_empty(&psta->asoc_list)) {
-			list_del_init(&psta->asoc_list);
-			pstapriv->asoc_list_cnt--;
-			updated = ap_free_sta(padapter, psta, false, reason);
-		}
-		spin_unlock_bh(&pstapriv->asoc_list_lock);
+	if (!psta)
+		return;
 
-		associated_clients_update(padapter, updated);
+	spin_lock_bh(&pstapriv->asoc_list_lock);
+	if (!list_empty(&psta->asoc_list)) {
+		list_del_init(&psta->asoc_list);
+		pstapriv->asoc_list_cnt--;
+		updated = ap_free_sta(padapter, psta, false, reason);
 	}
+	spin_unlock_bh(&pstapriv->asoc_list_lock);
+
+	associated_clients_update(padapter, updated);
 }
 
 static void OnAction_back(struct adapter *padapter, struct recv_frame *precv_frame)