net/mlx5: Remove useless validity check

All callers build xfrm attributes with help of mlx5e_ipsec_build_accel_xfrm_attrs()
function that ensure validity of attributes. There is no need to recheck
them again.

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