vmxnet: trivial annotation of protocol constant

Noticed by sparse:
drivers/net/vmxnet3/vmxnet3_drv.c:876:38: warning: cast from restricted __be16
drivers/net/vmxnet3/vmxnet3_drv.c:876:38: warning: cast from restricted __be16
drivers/net/vmxnet3/vmxnet3_drv.c:876:24: warning: restricted __be16 degrades to integer

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vmxnet3/vmxnet3_drv.c

@@ -873,7 +873,7 @@ vmxnet3_tq_xmit(struct sk_buff *skb, struct vmxnet3_tx_queue *tq,
 	count = VMXNET3_TXD_NEEDED(skb_headlen(skb)) +
 		skb_shinfo(skb)->nr_frags + 1;
 
-	ctx.ipv4 = (skb->protocol == __constant_ntohs(ETH_P_IP));
+	ctx.ipv4 = (skb->protocol == cpu_to_be16(ETH_P_IP));
 
 	ctx.mss = skb_shinfo(skb)->gso_size;
 	if (ctx.mss) {