ibmveth: Implement ethtool hooks to enable/disable checksum offload

This patch adds the appropriate ethtool hooks to allow for enabling/disabling
of hypervisor assisted checksum offload for TCP.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/net/ibmveth.h b/drivers/net/ibmveth.h
index 3f10f0f..43b068d 100644
--- a/drivers/net/ibmveth.h
+++ b/drivers/net/ibmveth.h
@@ -138,6 +138,7 @@
     struct ibmveth_buff_pool rx_buff_pool[IbmVethNumBufferPools];
     struct ibmveth_rx_q rx_queue;
     int pool_config;
+    int rx_csum;
 
     /* adapter specific stats */
     u64 replenish_task_cycles;