spi: rzv2m-csi: Make use of device_set_node

Use device_set_node instead of assigning controller->dev.of_node
directly because it also sets the firmware node.

Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@renesas.com>
Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/20230718192453.543549-5-fabrizio.castro.jz@renesas.com


Signed-off-by: Mark Brown <broonie@kernel.org>