dts:seco: Add base devicetree structure

BCS 746-001345

arch/arm64/boot/dts/Makefile

@@ -24,6 +24,7 @@ subdir-y += qcom
 subdir-y += realtek
 subdir-y += renesas
 subdir-y += rockchip
+subdir-y += seco
 subdir-y += seconorth
 subdir-y += socionext
 subdir-y += sprd

arch/arm64/boot/dts/seco/Makefile

+#
+# SECO Makefile
+#
+
+dts-dirs        += overlays
+subdir-y        := $(dts-dirs)
+DTC_FLAGS ?= -@ -H epapr

arch/arm64/boot/dts/seco/overlays/Makefile

+DTC_FLAGS ?= -@ -H epapr
+
+targets += dtbs dtbs_install
+targets += $(dtbo-y)
+
+always          := $(dtbo-y)
+clean-files     := *.dtbo