staging: r8188eu: simplify the sta loop in rtw_dequeue_xframe

Use list_for_each_entry_safe to iterate over the station entries in
function rtw_dequeue_xframe instead of coding the loop manually.

We have to use the safe version, the loop body may remove a station from
the list over which we iterate.
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Link: https://lore.kernel.org/r/20230123205342.229589-6-martin@kaiser.cxSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/r8188eu/core/rtw_xmit.c

@@ -1377,9 +1377,9 @@ static struct xmit_frame *dequeue_one_xmitframe(struct xmit_priv *pxmitpriv, str
 
 struct xmit_frame *rtw_dequeue_xframe(struct xmit_priv *pxmitpriv, struct hw_xmit *phwxmit_i)
 {
-	struct list_head *sta_plist, *sta_phead;
+	struct list_head *sta_phead;
 	struct hw_xmit *phwxmit;
-	struct tx_servq *ptxservq = NULL;
+	struct tx_servq *ptxservq, *tmp_txservq;
 	struct __queue *pframe_queue = NULL;
 	struct xmit_frame *pxmitframe = NULL;
 	struct adapter *padapter = pxmitpriv->adapter;
@@ -1401,10 +1401,8 @@ struct xmit_frame *rtw_dequeue_xframe(struct xmit_priv *pxmitpriv, struct hw_xmi
 		phwxmit = phwxmit_i + inx[i];
 
 		sta_phead = get_list_head(phwxmit->sta_queue);
-		sta_plist = sta_phead->next;
 
-		while (sta_phead != sta_plist) {
-			ptxservq = container_of(sta_plist, struct tx_servq, tx_pending);
+		list_for_each_entry_safe(ptxservq, tmp_txservq, sta_phead, tx_pending) {
 
 			pframe_queue = &ptxservq->sta_pending;
 
@@ -1418,8 +1416,6 @@ struct xmit_frame *rtw_dequeue_xframe(struct xmit_priv *pxmitpriv, struct hw_xmi
 					list_del_init(&ptxservq->tx_pending);
 				goto exit;
 			}
-
-			sta_plist = sta_plist->next;
 		}
 	}
 exit: