rv1108: Fix boot regression

Since commit 79030a486128 ("rockchip: Add Single boot image
(with binman, pad_cat)") the following boot regression is seen:

U-Boot 2020.04-rc3-00050-gd16e18ca6c-dirty (Mar 09 2020 - 11:40:07 -0300)

Model: Elgin RV1108 R1 board
DRAM:  128 MiB
initcall sequence 67fd12a0 failed at call 6000b927 (err=-22)

This happens because the above commit missed to include the
"rockchip-u-boot.dtsi" for rv1108, so include this file
like it done for other Rockchip SoC dtsi's.

Fixes: 79030a486128 ("rockchip: Add Single boot image (with binman, pad_cat)")
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/arch/arm/dts/rv1108-u-boot.dtsi b/arch/arm/dts/rv1108-u-boot.dtsi
new file mode 100644
index 0000000..41ac054
--- /dev/null
+++ b/arch/arm/dts/rv1108-u-boot.dtsi
@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019 Jagan Teki <jagan@amarulasolutions.com>
+ */
+
+#include "rockchip-u-boot.dtsi"