net: mv643xx_eth: Remove unused inline function sum16_as_be

commit 84411f73 ("net: mv643xx_eth: Avoid setting the initial TCP checksum")
left behind this, remove it.
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/marvell/mv643xx_eth.c

@@ -666,11 +666,6 @@ static inline unsigned int has_tiny_unaligned_frags(struct sk_buff *skb)
 	return 0;
 }
 
-static inline __be16 sum16_as_be(__sum16 sum)
-{
-	return (__force __be16)sum;
-}
-
 static int skb_tx_csum(struct mv643xx_eth_private *mp, struct sk_buff *skb,
 		       u16 *l4i_chk, u32 *command, int length)
 {