arm64: dts: renesas: Add HiHope RZ/G2M main board support

Basic support for the HiHope RZ/G2M main board:
  - Memory,
  - Main crystal,
  - Serial console

This patch also includes a dtsi common to both HiHope RZ/G2M
and RZ/G2N main boards.
Signed-off-by: Biju Das <biju.das@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-$(CONFIG_ARCH_R8A774A1) += r8a774a1-hihope-rzg2m.dtb
 dtb-$(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

arch/arm64/boot/dts/renesas/hihope-common.dtsi

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Device Tree Source for the HiHope RZ/G2[MN] main board common parts
+ *
+ * Copyright (C) 2019 Renesas Electronics Corp.
+ */
+
+/ {
+	aliases {
+		serial0 = &scif2;
+	};
+
+	chosen {
+		bootargs = "ignore_loglevel";
+		stdout-path = "serial0:115200n8";
+	};
+};
+
+&extal_clk {
+	clock-frequency = <16666666>;
+};
+
+&extalr_clk {
+	clock-frequency = <32768>;
+};
+
+&scif2 {
+	status = "okay";
+};
+
+&scif_clk {
+	clock-frequency = <14745600>;
+};

arch/arm64/boot/dts/renesas/r8a774a1-hihope-rzg2m.dts

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Device Tree Source for the HiHope RZ/G2M main board
+ *
+ * Copyright (C) 2019 Renesas Electronics Corp.
+ */
+
+/dts-v1/;
+#include "r8a774a1.dtsi"
+#include "hihope-common.dtsi"
+
+/ {
+	model = "HopeRun HiHope RZ/G2M main board based on r8a774a1";
+	compatible = "hoperun,hihope-rzg2m", "renesas,r8a774a1";
+
+	memory@48000000 {
+		device_type = "memory";
+		/* first 128MB is reserved for secure area. */
+		reg = <0x0 0x48000000 0x0 0x78000000>;
+	};
+
+	memory@600000000 {
+		device_type = "memory";
+		reg = <0x6 0x00000000 0x0 0x80000000>;
+	};
+};