drm/mediatek: Convert legacy DRM logging to drm_* helpers in mtk_crtc.c

drm/mediatek: Convert legacy DRM logging to drm_* helpers in mtk_crtc.c

Replace DRM_ERROR() and DRM_DEBUG_DRIVER() calls in
drivers/gpu/drm/mediatek/mtk_crtc.c with the corresponding drm_err()
and drm_dbg_driver() helpers.

The drm_*() logging helpers take a struct drm_device * argument,
allowing the DRM core to prefix log messages with the correct device
name and instance. This is required to correctly distinguish log
messages on systems with multiple GPUs.

This change aligns the Mediatek DRM driver with the DRM TODO item:
"Convert logging to drm_* functions with drm_device parameter".

Reported-by: kernel test robot <lkp@intel.com>
Closes:
https://lore.kernel.org/oe-kbuild-all/202512220515.z3QybJ8I-lkp@intel.com/
Signed-off-by: Abhishek Rajput <abhiraj21put@gmail.com>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20251223095434.492041-1-abhiraj21put@gmail.com/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>