ASoC: rsnd: fix OF node reference leak in rsnd_ssiu_probe()

ASoC: rsnd: fix OF node reference leak in rsnd_ssiu_probe()

rsnd_ssiu_probe() leaks an OF node reference obtained by
rsnd_ssiu_of_node(). The node reference is acquired but
never released across all return paths.

Fix it by declaring the device node with the __free(device_node)
cleanup construct to ensure automatic release when the variable goes
out of scope.

Fixes: 4e7788fb8018 ("ASoC: rsnd: add SSIU BUSIF support")
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://patch.msgid.link/20251112065709.1522-1-vulab@iscas.ac.cn
Signed-off-by: Mark Brown <broonie@kernel.org>