net/mlx5: Fix SFs kernel documentation error

Indent SFs probe code example in order to fix the below error:

Documentation/networking/device_drivers/ethernet/mellanox/mlx5/switchdev.rst:57: ERROR: Unexpected indentation.
Documentation/networking/device_drivers/ethernet/mellanox/mlx5/switchdev.rst:61: ERROR: Unexpected indentation.

Fixes: e71383fb ("net/mlx5: Light probe local SFs")
Signed-off-by: Shay Drory <shayd@nvidia.com>
Reviewed-by: Rahul Rameshbabu <rrameshbabu@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Reviewed-by: Automatic Verification <verifier@nvidia.com>
Reviewed-by: Gal Pressman <gal@nvidia.com>