tokenring/3c359.c: fix allocation null check

Fixed typo when allocating rx_ring, tx_ring was checked for null instead.
Signed-off-by: NJirka Pirko <jirka@pirko.cz>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/tokenring/3c359.c

@@ -644,7 +644,7 @@ static int xl_open(struct net_device *dev)
 		return -ENOMEM;
 	}
 	xl_priv->xl_rx_ring = kzalloc((sizeof(struct xl_rx_desc) * XL_RX_RING_SIZE) +7, GFP_DMA | GFP_KERNEL);
-	if (xl_priv->xl_tx_ring == NULL) {
+	if (xl_priv->xl_rx_ring == NULL) {
 		printk(KERN_WARNING "%s: Not enough memory to allocate rx buffers.\n",
 				     dev->name);
 		free_irq(dev->irq,dev);