riscv: dts: sophgo: add Huashan Pi board device tree

Add initial device tree files for the Huashan Pi board.

Note: The boot of CV1812H chip needs a rtos firmware for coprocessor to
function properly. To make the soc happy, reserved the last 2M memory
for the rtos firmware.
Signed-off-by: Inochi Amaoto <inochiama@outlook.com>
Link: https://en.sophgo.com/product/introduce/huashan.html
Link: https://en.sophgo.com/product/introduce/cv181xH.html
Link: https://github.com/milkv-duo/duo-buildroot-sdk/blob/develop/build/boards/cv181x/cv1812h_wevb_0007a_emmc_huashan/memmap.py#L15Reviewed-by: Jisheng Zhang <jszhang@kernel.org>
Acked-by: Chen Wang <unicorn_wang@outlook.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>

arch/riscv/boot/dts/sophgo/Makefile

 # SPDX-License-Identifier: GPL-2.0
 dtb-$(CONFIG_ARCH_SOPHGO) += cv1800b-milkv-duo.dtb
+dtb-$(CONFIG_ARCH_SOPHGO) += cv1812h-huashan-pi.dtb
 dtb-$(CONFIG_ARCH_SOPHGO) += sg2042-milkv-pioneer.dtb

arch/riscv/boot/dts/sophgo/cv1812h-huashan-pi.dts

+// SPDX-License-Identifier: (GPL-2.0 OR MIT)
+/*
+ * Copyright (C) 2023 Inochi Amaoto <inochiama@outlook.com>
+ */
+
+/dts-v1/;
+
+#include "cv1812h.dtsi"
+
+/ {
+	model = "Huashan Pi";
+	compatible = "sophgo,huashan-pi", "sophgo,cv1812h";
+
+	aliases {
+		gpio0 = &gpio0;
+		gpio1 = &gpio1;
+		gpio2 = &gpio2;
+		gpio3 = &gpio3;
+		serial0 = &uart0;
+		serial1 = &uart1;
+		serial2 = &uart2;
+		serial3 = &uart3;
+		serial4 = &uart4;
+	};
+
+	chosen {
+		stdout-path = "serial0:115200n8";
+	};
+
+	reserved-memory {
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges;
+
+		coprocessor_rtos: region@8fe00000 {
+			reg = <0x8fe00000 0x200000>;
+			no-map;
+		};
+	};
+};
+
+&osc {
+	clock-frequency = <25000000>;
+};
+
+&uart0 {
+	status = "okay";
+};