rockchip: rk3399: Move u-boot, dm-pre-reloc of uart0, uart2

u-boot,dm-pre-reloc for uart0, uart2 indeed u-boot specific
properties. Move them into rk3399-u-boot.dtsi so the boards
which enabled these node will available during SPL.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/arch/arm/dts/rk3399-u-boot.dtsi b/arch/arm/dts/rk3399-u-boot.dtsi
index 0786c11..fcfce9a 100644
--- a/arch/arm/dts/rk3399-u-boot.dtsi
+++ b/arch/arm/dts/rk3399-u-boot.dtsi
@@ -10,3 +10,11 @@
 &spi1 {
 	u-boot,dm-pre-reloc;
 };
+
+&uart0 {
+	u-boot,dm-pre-reloc;
+};
+
+&uart2 {
+	u-boot,dm-pre-reloc;
+};