net/mlx5: Remove the repeated declaration

Function 'mlx5_esw_vport_match_metadata_supported' and
'mlx5_esw_offloads_vport_metadata_set' are declared twice, so remove
the repeated declaration and blank line.

Cc: Saeed Mahameed <saeedm@nvidia.com>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>