mlx5e: Fix sparse warnings in mlx5e_handle_csum().

>> drivers/net/ethernet/mellanox/mlx5/core/en_rx.c:173:44: sparse: incorrect type in argument 1 (different base types)
   drivers/net/ethernet/mellanox/mlx5/core/en_rx.c:173:44:    expected restricted __sum16 [usertype] n
   drivers/net/ethernet/mellanox/mlx5/core/en_rx.c:173:44:    got restricted __be16 [usertype] check_sum

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx5/core/en_rx.c

@@ -170,7 +170,7 @@ static inline void mlx5e_handle_csum(struct net_device *netdev,
 		skb->ip_summed = CHECKSUM_UNNECESSARY;
 	} else if (is_first_ethertype_ip(skb)) {
 		skb->ip_summed = CHECKSUM_COMPLETE;
-		skb->csum = csum_unfold(cqe->check_sum);
+		skb->csum = csum_unfold((__force __sum16)cqe->check_sum);
 		rq->stats.csum_sw++;
 	} else {
 		goto csum_none;