net/mlx5e: Set decap action based on attr for sample

Currently decap action is set based on tunnel_id. That means it is
set unconditionally. But for decap, ct and sample actions, decap is
done before ct. No need to decap again in sample.

And the actions are set correctly when parsing. So set decap action
based on attr instead of tunnel_id.

Fixes: 2741f223 ("net/mlx5e: TC, Support sample offload action for tunneled traffic")
Signed-off-by: Chris Mi <cmi@nvidia.com>
Reviewed-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>