rk3288: tinker: Enable HDMI output

Enable HDMI output for Tinker RK3288 board.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/include/configs/tinker_rk3288.h b/include/configs/tinker_rk3288.h
index f8a55a2..f1095cc 100644
--- a/include/configs/tinker_rk3288.h
+++ b/include/configs/tinker_rk3288.h
@@ -6,7 +6,11 @@
 #ifndef __CONFIG_H
 #define __CONFIG_H
 
-#define ROCKCHIP_DEVICE_SETTINGS
+#define ROCKCHIP_DEVICE_SETTINGS \
+		"stdin=serial,cros-ec-keyb\0" \
+		"stdout=serial,vidconsole\0" \
+		"stderr=serial,vidconsole\0"
+
 #include <configs/rk3288_common.h>
 
 #undef BOOT_TARGET_DEVICES