net/mlx5e: Support IPsec TX packet offload in tunnel mode

Extend mlx5 driver with logic to support IPsec TX packet offload
in tunnel mode.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Reviewed-by: Sridhar Samudrala <sridhar.samudrala@intel.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>