arm64: dts: r8a7796-salvator-xs: Add R-Car M3 ES3.0 (2 x 4 GiB) support

This patch adds initial support for the Renesas Salvator-X 2nd version
development board equipped with an R-Car M3 ES3.0 SiP of 8GiB (2 x 4 GiB)
memory model.

The memory map is as follows:
    Bank0: 4GiB RAM : 0x000048000000 -> 0x000bfffffff
                      0x000480000000 -> 0x004ffffffff
    Bank1: 4GiB RAM : 0x000600000000 -> 0x006ffffffff

Signed-off-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>

arch/arm64/boot/dts/renesas/Makefile

@@ -9,6 +9,7 @@ dtb-$(CONFIG_ARCH_R8A7795) += r8a7795-es1-h3ulcb-kf.dtb
 dtb-$(CONFIG_ARCH_R8A7796) += r8a7796-salvator-x.dtb r8a7796-m3ulcb.dtb
 dtb-$(CONFIG_ARCH_R8A7796) += r8a7796-m3ulcb-kf.dtb
 dtb-$(CONFIG_ARCH_R8A7796) += r8a7796-salvator-xs.dtb
+dtb-$(CONFIG_ARCH_R8A7796) += r8a7796-salvator-xs-2x4g.dtb
 dtb-$(CONFIG_ARCH_R8A77965) += r8a77965-salvator-x.dtb r8a77965-salvator-xs.dtb
 dtb-$(CONFIG_ARCH_R8A77970) += r8a77970-eagle.dtb r8a77970-v3msk.dtb
 dtb-$(CONFIG_ARCH_R8A77980) += r8a77980-condor.dtb r8a77980-v3hsk.dtb

arch/arm64/boot/dts/renesas/r8a7796-salvator-xs-2x4g.dts

@@ -0,0 +1,32 @@
+/*
+ * Device Tree Source for the Salvator-X 2nd version board with R-Car M3 ES3.0
+ *
+ * Copyright (C) 2018 Renesas Electronics Corp.
+ *
+ * This file is licensed under the terms of the GNU General Public License
+ * version 2.  This program is licensed "as is" without any warranty of any
+ * kind, whether express or implied.
+ */
+
+#include "r8a7796-salvator-xs.dts"
+
+/ {
+	model = "Renesas Salvator-X 2nd version board based on r8a7796 ES3.0+ with 8GiB (2 x 4 GiB)";
+	compatible = "renesas,salvator-xs", "renesas,r8a7796";
+
+	memory@48000000 {
+		device_type = "memory";
+		/* first 128MB is reserved for secure area. */
+		reg = <0x0 0x48000000 0x0 0x78000000>;
+	};
+
+	memory@400000000 {
+		device_type = "memory";
+		reg = <0x4 0x80000000 0x0 0x80000000>;
+	};
+
+	memory@600000000 {
+		device_type = "memory";
+		reg = <0x6 0x00000000 0x1 0x00000000>;
+	};
+};