drm/logicvc: Fix device node reference leak in logicvc_drm_config_parse()

drm/logicvc: Fix device node reference leak in logicvc_drm_config_parse()

The logicvc_drm_config_parse() function calls of_get_child_by_name() to
find the "layers" node but fails to release the reference, leading to a
device node reference leak.

Fix this by using the __free(device_node) cleanup attribute to automatic
release the reference when the variable goes out of scope.

Fixes: efeeaefe9be5 ("drm: Add support for the LogiCVC display controller")
Signed-off-by: Felix Gu <ustc.gu@gmail.com>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>
Link: https://patch.msgid.link/20260130-logicvc_drm-v1-1-04366463750c@gmail.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>