staging: rtl8188eu: use safe iterator in dequeue_xmitframes_to_sleeping_queue()

On some code paths the xmitframe_enqueue_for_sleeping_sta() function can
call list_del_init(&pxmitframe->list) which would lead to a forever loop
because "pxmitframe" is the list iterator.  Use the _safe version of the
iterator to prevent this.

Fixes: 23017c88 ("staging: rtl8188eu: Use list iterators and helpers")
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/YL5ixzKaYKkpHhky@mwandaSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8188eu/core/rtw_xmit.c

@@ -1729,17 +1729,15 @@ int xmitframe_enqueue_for_sleeping_sta(struct adapter *padapter, struct xmit_fra
 
 static void dequeue_xmitframes_to_sleeping_queue(struct adapter *padapter, struct sta_info *psta, struct __queue *pframequeue)
 {
-	struct list_head *plist, *phead;
+	struct list_head *phead;
 	u8	ac_index;
 	struct tx_servq	*ptxservq;
 	struct pkt_attrib	*pattrib;
-	struct xmit_frame	*pxmitframe;
+	struct xmit_frame	*pxmitframe, *n;
 	struct hw_xmit *phwxmits =  padapter->xmitpriv.hwxmits;
 
 	phead = get_list_head(pframequeue);
-	list_for_each(plist, phead) {
-		pxmitframe = list_entry(plist, struct xmit_frame, list);
-
+	list_for_each_entry_safe(pxmitframe, n, phead, list) {
 		xmitframe_enqueue_for_sleeping_sta(padapter, pxmitframe);
 
 		pattrib = &pxmitframe->attrib;