net: sxgbe: fix error paths in sxgbe_platform_probe()

We need to use post-decrement to ensure that irq_dispose_mapping is
also called on priv->rxq[0]->irq_no; moreover, if one of the above for
loops failed already at i==0 (so we reach one of these labels with
that value of i), we'll enter an essentially infinite loop of
out-of-bounds accesses.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Reviewed-by: Francois Romieu <romieu@fr.zoreil.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/samsung/sxgbe/sxgbe_platform.c

@@ -155,11 +155,11 @@ static int sxgbe_platform_probe(struct platform_device *pdev)
 	return 0;
 
 err_rx_irq_unmap:
-	while (--i)
+	while (i--)
 		irq_dispose_mapping(priv->rxq[i]->irq_no);
 	i = SXGBE_TX_QUEUES;
 err_tx_irq_unmap:
-	while (--i)
+	while (i--)
 		irq_dispose_mapping(priv->txq[i]->irq_no);
 	irq_dispose_mapping(priv->irq);
 err_drv_remove: