spi: spi-s3c64xx.c: Remove of_node_put for auto cleanup

spi: spi-s3c64xx.c: Remove of_node_put for auto cleanup

Use the scope based of_node_put() cleanup in s3c64xx_spi_csinfo to
automatically release the device node with the __free() cleanup handler
Initialize data_np at the point of declaration for clarity of scope.

This change reduces the risk of memory leaks and simplifies the code by
removing manual node put call.

Suggested-by: Julia Lawall <julia.lawall@inria.fr>
Signed-off-by: Shivani Gupta <shivani07g@gmail.com>
Link: https://lore.kernel.org/r/20240418000505.731724-1-shivani07g@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>