staging: r8188eu: use sa instead of Addr2

For management frames, Addr2 is the Source Address (SA).

Use sa from the mgmt structure and remove the GetAddr2Ptr call.
GetAddr2Ptr is a driver-specific function that we should eventually
remove.
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Tested-by: Philipp Hortmann <philipp.g.hortmann@gmail.com> # Edimax N150
Acked-by: Pavel Skripkin <paskripkin@gmail.com>
Link: https://lore.kernel.org/r/20221015152440.232281-5-martin@kaiser.cxSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/r8188eu/core/rtw_mlme_ext.c

@@ -1479,7 +1479,7 @@ unsigned int OnDeAuth(struct adapter *padapter, struct recv_frame *precv_frame)
 		struct sta_info *psta;
 		struct sta_priv *pstapriv = &padapter->stapriv;
 
-		psta = rtw_get_stainfo(pstapriv, GetAddr2Ptr(pframe));
+		psta = rtw_get_stainfo(pstapriv, mgmt->sa);
 		if (psta) {
 			u8 updated = 0;