rtl818x_pci: Fix a memory leak in rtl8180_init_rx_ring

When dev_alloc_skb or pci_dma_mapping_error in rtl8180_init_rx_ring fails,
the memory allocated by pci_zalloc_consistent is not freed.

This patch fixes the bug by adding pci_free_consistent
in error handling code.
Signed-off-by: Jia-Ju Bai <baijiaju1990@163.com>
Signed-off-by: Julian Calaby <julian.calaby@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/realtek/rtl818x/rtl8180/dev.c

@@ -1018,6 +1018,8 @@ static int rtl8180_init_rx_ring(struct ieee80211_hw *dev)
 		dma_addr_t *mapping;
 		entry = priv->rx_ring + priv->rx_ring_sz*i;
 		if (!skb) {
+			pci_free_consistent(priv->pdev, priv->rx_ring_sz * 32,
+					priv->rx_ring, priv->rx_ring_dma);
 			wiphy_err(dev->wiphy, "Cannot allocate RX skb\n");
 			return -ENOMEM;
 		}
@@ -1028,6 +1030,8 @@ static int rtl8180_init_rx_ring(struct ieee80211_hw *dev)
 
 		if (pci_dma_mapping_error(priv->pdev, *mapping)) {
 			kfree_skb(skb);
+			pci_free_consistent(priv->pdev, priv->rx_ring_sz * 32,
+					priv->rx_ring, priv->rx_ring_dma);
 			wiphy_err(dev->wiphy, "Cannot map DMA for RX skb\n");
 			return -ENOMEM;
 		}