drm/stm: ltdc: unify log system

DRM_ERROR and similar are deprecated.  Use drm_dev based logging.

Link: https://lore.kernel.org/r/20250821130356.883553-1-raphael.gallais-pou@foss.st.com


Acked-by: Yannick Fertre <yannick.fertre@foss.st.com>
Link: https://lore.kernel.org/r/20250825132951.547899-1-raphael.gallais-pou@foss.st.com


Signed-off-by: Raphael Gallais-Pou <raphael.gallais-pou@foss.st.com>