rockchip: generate u-boot-rockchip.bin with binman for ARM64 boards

This allows to build u-boot-rockchip.bin binary with binman for Rockchip
ARM64 boards instead of the legacy Makefile way.

Cc: Quentin Schulz <foss+uboot@0leil.net>
Signed-off-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/dts/rk3308-u-boot.dtsi b/arch/arm/dts/rk3308-u-boot.dtsi
index 4bfad31..ab5bfc2 100644
--- a/arch/arm/dts/rk3308-u-boot.dtsi
+++ b/arch/arm/dts/rk3308-u-boot.dtsi
@@ -3,6 +3,8 @@
  *(C) Copyright 2019 Rockchip Electronics Co., Ltd
  */
 
+#include "rockchip-u-boot.dtsi"
+
 / {
 	aliases {
 		mmc0 = &emmc;