net/mlx5: DR, Add modify header argument pointer to actions attributes

net/mlx5: DR, Add modify header argument pointer to actions attributes

While building the actions, add the pointer of the arguments for
accelerated modify list action into the action's attributes.
This will be used later on while building the specific STE
for this action.

Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Alex Vesker <valex@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>