ARM: opos6ul: make the board boot again

Commit 9faa43c4b5e5 ("ARM: dts: i.MX6UL: U-Boot specific dts for u-boot,
dm-spl") removes the u-boot,dm-spl properties from the imx6ul.dtsi file
and breaks the OPOS6UL board.
Add the u-boot,dm-spl properties into *-u-boot.dts files to make the
board boot again.

Fixes: commit 9faa43c4b5e5 ("ARM: dts: i.MX6UL: U-Boot specific dts for u-boot, dm-spl")
Signed-off-by: Sébastien Szymanski <sebastien.szymanski@armadeus.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Stefano Babic <sbabic@denx.de>
diff --git a/arch/arm/dts/imx6ul-opos6uldev-u-boot.dtsi b/arch/arm/dts/imx6ul-opos6uldev-u-boot.dtsi
new file mode 100644
index 0000000..da8b039
--- /dev/null
+++ b/arch/arm/dts/imx6ul-opos6uldev-u-boot.dtsi
@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Device Tree Source extras for U-Boot for the OPOS6ULDev board
+ *
+ * Copyright (C) 2018 Armadeus Systems <support@armadeus.com>
+ */
+
+#include "imx6ul-opos6ul-u-boot.dtsi"
+
+&aips1 {
+	u-boot,dm-spl;
+
+	spba-bus@02000000 {
+		u-boot,dm-spl;
+	};
+};
+
+&pinctrl_uart1 {
+	u-boot,dm-spl;
+};
+
+&uart1 {
+	u-boot,dm-spl;
+};