net/mlx5: Introduce hierarchy level tracking on scheduling nodes

Add a `level` field to `mlx5_esw_sched_node` to track the hierarchy
depth of each scheduling node. This allows enforcement of the
scheduling depth constraints based on `log_esw_max_sched_depth`.

Modify `esw_qos_node_set_parent()` and `__esw_qos_alloc_node()` to
correctly assign hierarchy levels. Ensure that nodes inherit their
parent’s level incrementally.

Signed-off-by: Carolina Jubran <cjubran@nvidia.com>
Reviewed-by: Cosmin Ratiu <cratiu@nvidia.com>
Reviewed-by: Dragos Tatulea <dtatulea@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://patch.msgid.link/1741642016-44918-3-git-send-email-tariqt@nvidia.com


Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>