net/mlx5e: Remove unused mlx5e_tc_flow_action struct

Commit 67efaf45 ("net/mlx5e: TC, Remove CT action reordering")
removed the usage of mlx5e_tc_flow_action struct, remove the struct as
well.

Signed-off-by: Gal Pressman <gal@nvidia.com>
Reviewed-by: Cosmin Ratiu <cratiu@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>