arm64: dts: renesas: Add Si-Linux EK874 board support

The EK874 development kit from Silicon Linux is made of CAT874 (the main
board) and CAT875 (the sub board that goes on top of CAT874).
Signed-off-by: Biju Das <biju.das@bp.renesas.com>
Signed-off-by: Fabrizio Castro <fabrizio.castro@bp.renesas.com>
Reviewed-by: Chris Paterson <Chris.Paterson2@renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm64/boot/dts/renesas/Makefile

 # SPDX-License-Identifier: GPL-2.0
-dtb-$(CONFIG_ARCH_R8A774C0) += r8a774c0-cat874.dtb
+dtb-$(CONFIG_ARCH_R8A774C0) += r8a774c0-cat874.dtb r8a774c0-ek874.dtb
 dtb-$(CONFIG_ARCH_R8A7795) += r8a7795-salvator-x.dtb r8a7795-h3ulcb.dtb
 dtb-$(CONFIG_ARCH_R8A7795) += r8a7795-h3ulcb-kf.dtb
 dtb-$(CONFIG_ARCH_R8A7795) += r8a7795-salvator-xs.dtb

arch/arm64/boot/dts/renesas/cat875.dtsi

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Device Tree Source for the Silicon Linux sub board for CAT874 (CAT875)
+ *
+ * Copyright (C) 2019 Renesas Electronics Corp.
+ */
+
+/ {
+	model = "Silicon Linux sub board for CAT874 (CAT875)";
+};

arch/arm64/boot/dts/renesas/r8a774c0-ek874.dts

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Device Tree Source for the Silicon Linux RZ/G2E evaluation kit (EK874)
+ *
+ * Copyright (C) 2019 Renesas Electronics Corp.
+ */
+
+#include "r8a774c0-cat874.dts"
+#include "cat875.dtsi"
+
+/ {
+	model = "Silicon Linux RZ/G2E evaluation kit EK874 (CAT874 + CAT875)";
+	compatible = "si-linux,cat875", "si-linux,cat874", "renesas,r8a774c0";
+};