staging: r8188eu: remove dead assignment

There's no point in moving xmitframe_plist to the next list element.
xmitframe_plist is not used any more after this assignment.
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/20230123205342.229589-10-martin@kaiser.cxSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/r8188eu/core/rtw_xmit.c

@@ -1365,11 +1365,7 @@ static struct xmit_frame *dequeue_one_xmitframe(struct tx_servq *ptxservq, struc
 
 	if (xmitframe_phead != xmitframe_plist) {
 		pxmitframe = container_of(xmitframe_plist, struct xmit_frame, list);
-
-		xmitframe_plist = xmitframe_plist->next;
-
 		list_del_init(&pxmitframe->list);
-
 		ptxservq->qcnt--;
 	}
 	return pxmitframe;