staging: rtl8188eu: use safe iterator in rtl8188eu_xmitframe_complete()

This loop calls rtw_free_xmitframe(pxmitpriv, pxmitframe) which removes
"pxmitframe" (our list iterator) from the list.  So to prevent a forever
loop we need to use a safe list iterator.

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/YL5i8W7BNla2DlrW@mwandaSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/rtl8188eu/hal/rtl8188eu_xmit.c

@@ -414,6 +414,7 @@ bool rtl8188eu_xmitframe_complete(struct adapter *adapt,
 				  struct xmit_priv *pxmitpriv)
 {
 	struct xmit_frame *pxmitframe = NULL;
+	struct xmit_frame *n;
 	struct xmit_frame *pfirstframe = NULL;
 	struct xmit_buf *pxmitbuf;
 
@@ -422,7 +423,7 @@ bool rtl8188eu_xmitframe_complete(struct adapter *adapt,
 	struct sta_info *psta = NULL;
 	struct tx_servq *ptxservq = NULL;
 
-	struct list_head *xmitframe_plist = NULL, *xmitframe_phead = NULL;
+	struct list_head *xmitframe_phead = NULL;
 
 	u32 pbuf;	/*  next pkt address */
 	u32 pbuf_tail;	/*  last pkt tail */
@@ -507,10 +508,7 @@ bool rtl8188eu_xmitframe_complete(struct adapter *adapt,
 	spin_lock_bh(&pxmitpriv->lock);
 
 	xmitframe_phead = get_list_head(&ptxservq->sta_pending);
-	list_for_each(xmitframe_plist, xmitframe_phead) {
-		pxmitframe = list_entry(xmitframe_plist, struct xmit_frame,
-					list);
-
+	list_for_each_entry_safe(pxmitframe, n, xmitframe_phead, list) {
 		pxmitframe->agg_num = 0; /*  not first frame of aggregation */
 		pxmitframe->pkt_offset = 0; /*  not first frame of aggregation, no need to reserve offset */