net/mlx5: Delete metadata handling logic

Remove specific to FPGS IPsec metadata handling logic which is not
required for mlx5 NICs devices.

Link: https://lore.kernel.org/r/fe67a1de4fc6032a940e18c8a6461a1ccf902fc4.1649232994.git.leonro@nvidia.com


Reviewed-by: Raed Salem <raeds@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>