video: stm32_ltdc: Convert to use APIs which support live DT

Use ofnode_ or dev_ APIs instead of fdt_ and fdtdec_ APIs so that the
driver can support live DT.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Reviewed-by: Yannick Fertré <yannick.fertre@st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>
diff --git a/drivers/video/stm32/stm32_ltdc.c b/drivers/video/stm32/stm32_ltdc.c
index 2f3427a..7fff735 100644
--- a/drivers/video/stm32/stm32_ltdc.c
+++ b/drivers/video/stm32/stm32_ltdc.c
@@ -366,8 +366,7 @@
 
 	ret = panel_get_display_timing(panel, &timings);
 	if (ret) {
-		ret = fdtdec_decode_display_timing(gd->fdt_blob,
-						   dev_of_offset(panel),
+		ret = ofnode_decode_display_timing(dev_ofnode(panel),
 						   0, &timings);
 		if (ret) {
 			dev_err(dev, "decode display timing error %d\n", ret);