dts: db820c: added smem nodes

Added necessary nodes for Qualcomm smem driver.

Signed-off-by: Ramon Fried <ramon.fried@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/dts/dragonboard820c-uboot.dtsi b/arch/arm/dts/dragonboard820c-uboot.dtsi
index 97394cc..d60aa04 100644
--- a/arch/arm/dts/dragonboard820c-uboot.dtsi
+++ b/arch/arm/dts/dragonboard820c-uboot.dtsi
@@ -6,6 +6,10 @@
  */
 
 / {
+	smem {
+		u-boot,dm-pre-reloc;
+	};
+
 	soc {
 		u-boot,dm-pre-reloc;