drm/mxsfb/lcdif: simplify remote pointer management using __free

drm/mxsfb/lcdif: simplify remote pointer management using __free

Putting the remote device_node reference requires a of_node_put(remote) in
two places. Use a cleanup action to simplify the code.

Reviewed-by: Liu Ying <victor.liu@nxp.com>
Tested-by: Martyn Welch <martyn.welch@collabora.com>
Tested-by: Alexander Stein <alexander.stein@ew.tq-group.com> # TQMa8MPxL/MBa8MPxL
Link: https://patch.msgid.link/20260407-drm-lcdif-dbanc-v4-1-247a16e61ef9@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>