rockchip: add u-boot specific dts for rk3036 sdk

Add this dts to enable debug uart releated devices
before relocation.

Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>

arch/arm/dts/rk3036-sdk-u-boot.dtsi

@@ -0,0 +1,11 @@
+&uart2 {
+	u-boot,dm-pre-reloc;
+};
+
+&grf {
+	u-boot,dm-pre-reloc;
+};
+
+&pinctrl {
+	u-boot,dm-pre-reloc;
+};