net/mlx5: Remove FPGA ipsec specific statistics

Delete the statistics that is not used anymore.

Link: https://lore.kernel.org/r/3f194752881e095910c887dd5cede1dcba6acaf3.1649232994.git.leonro@nvidia.com


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