drm/bridge: lt9611: fix programming of video modes

Program the upper part of the hfront_porch into the proper register.

Fixes: 23278bf5 ("drm/bridge: Introduce LT9611 DSI to HDMI bridge")
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230118081658.2198520-5-dmitry.baryshkov@linaro.org

drivers/gpu/drm/bridge/lontium-lt9611.c

@@ -187,7 +187,8 @@ static void lt9611_mipi_video_setup(struct lt9611 *lt9611,
 
 	regmap_write(lt9611->regmap, 0x8319, (u8)(hfront_porch % 256));
 
-	regmap_write(lt9611->regmap, 0x831a, (u8)(hsync_porch / 256));
+	regmap_write(lt9611->regmap, 0x831a, (u8)(hsync_porch / 256) |
+						((hfront_porch / 256) << 4));
 	regmap_write(lt9611->regmap, 0x831b, (u8)(hsync_porch % 256));
 }