drm/bridge: fsl-ldb: Enable split mode for LVDS dual link

When LVDS dual link is used, we have to enable the LDB_CTRL_SPLIT_MODE bit.

Fixes: 463db5c2ed4a ("drm: bridge: ldb: Implement simple Freescale i.MX8MP LDB bridge")
Cc: Andrzej Hajda <[e-mail]>
Cc: Neil Armstrong <[e-mail]>
Cc: Robert Foss <[e-mail]>
Cc: Laurent Pinchart <[e-mail]>
Cc: Jonas Karlman <[e-mail]>
Cc: Jernej Skrabec <[e-mail]>
Cc: David Airlie <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: Sam Ravnborg <[e-mail]>
Cc: Marek Vasut <[e-mail]>
Cc: NXP Linux Team <[e-mail]>
Signed-off-by: Liu Ying <[e-mail]>
Reviewed-by: Marek Vasut <[e-mail]>
Signed-off-by: Neil Armstrong <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/bridge/fsl-ldb.c

···
 	reg = LDB_CTRL_CH0_ENABLE;
 
 	if (fsl_ldb->lvds_dual_link)
-		reg |= LDB_CTRL_CH1_ENABLE;
+		reg |= LDB_CTRL_CH1_ENABLE | LDB_CTRL_SPLIT_MODE;
 
 	if (lvds_format_24bpp) {
 		reg |= LDB_CTRL_CH0_DATA_WIDTH;