rockchip: rv1108: Enable grf as pre-reloc node

The grf node will be used before relocate, enable it in dts.
Signed-off-by: NKever Yang <kever.yang@rock-chips.com>

arch/arm/dts/rv1108-u-boot.dtsi

@@ -4,3 +4,7 @@
  */
 
 #include "rockchip-u-boot.dtsi"
+
+&grf {
+	u-boot,dm-pre-reloc;
+};