net/mlx4_en: fix sparse warning on a cast which truncates bits from constant value

the MLX4_EN_WOL_DO_MODIFY flag which is defined through enum targets
bit 63, this triggers a "cast truncate bits from constant value
(8000000000000000 becomes 0)" warning from sparse, fix that by using
define instead of enum.
Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/mlx4_en.h

@@ -485,9 +485,9 @@ struct mlx4_en_priv {
 enum mlx4_en_wol {
 	MLX4_EN_WOL_MAGIC = (1ULL << 61),
 	MLX4_EN_WOL_ENABLED = (1ULL << 62),
-	MLX4_EN_WOL_DO_MODIFY = (1ULL << 63),
 };
 
+#define MLX4_EN_WOL_DO_MODIFY (1ULL << 63)
 
 void mlx4_en_destroy_netdev(struct net_device *dev);
 int mlx4_en_init_netdev(struct mlx4_en_dev *mdev, int port,