iwmc3200wifi: hardware does not support IP checksum

The iwmc3200wifi hardware doesn't support IP checksum. So mark the
skb->ip_summed to CHECKSUM_NONE instead of CHECKSUM_UNNECESSARY.

Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/iwmc3200wifi/rx.c

@@ -1359,7 +1359,7 @@ static void iwm_rx_process_packet(struct iwm_priv *iwm,
 
 		skb->dev = iwm_to_ndev(iwm);
 		skb->protocol = eth_type_trans(skb, ndev);
-		skb->ip_summed = CHECKSUM_UNNECESSARY;
+		skb->ip_summed = CHECKSUM_NONE;
 		memset(skb->cb, 0, sizeof(skb->cb));
 
 		ndev->stats.rx_packets++;