net/mlx5e: Directly get flow_steering struct as input when init/cleanup ethtool steering

Let both mlx5e_ethtool_init_steering and mlx5e_ethtool_cleanup_steering
get ethtool steering struct as input instead of priv, as passing priv is
obsolete.
Also modify other function through the flow similarly.

Signed-off-by: Lama Kayal <lkayal@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>