net/mlx5: Restrict domain list insertion to root TSAR ancestors

Update the logic for adding rate groups to the E-Switch domain list,
ensuring only groups with the root Transmit Scheduling Arbiter as their
parent are included.

Signed-off-by: Carolina Jubran <cjubran@nvidia.com>
Reviewed-by: Cosmin Ratiu <cratiu@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Reviewed-by: Daniel Machon <daniel.machon@microchip.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>