riscv: dts: eswin: add HiFive Premier P550 board device tree

Add minimal device tree for HiFive Premier P550 Development board

Currently the data populated in this DT file is for UART.

Signed-off-by: Min Lin <linmin@eswincomputing.com>
Co-developed-by: Pinkesh Vaghela <pinkesh.vaghela@einfochips.com>
Signed-off-by: Pinkesh Vaghela <pinkesh.vaghela@einfochips.com>
Tested-by: Samuel Holland <samuel.holland@sifive.com>
Tested-by: Ariel D'Alessandro <ariel.dalessandro@collabora.com>
Reviewed-by: Samuel Holland <samuel.holland@sifive.com>
Link: https://lore.kernel.org/r/20250825132427.1618089-7-pinkesh.vaghela@einfochips.com
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/riscv/boot/dts/Makefile

@@ -2,6 +2,7 @@
 subdir-y += allwinner
 subdir-y += andes
 subdir-y += canaan
+subdir-y += eswin
 subdir-y += microchip
 subdir-y += renesas
 subdir-y += sifive

arch/riscv/boot/dts/eswin/Makefile

@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0
+dtb-$(CONFIG_ARCH_ESWIN) += eic7700-hifive-premier-p550.dtb

arch/riscv/boot/dts/eswin/eic7700-hifive-premier-p550.dts

@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: (GPL-2.0 OR MIT)
+/*
+ * Copyright (c) 2024, Beijing ESWIN Computing Technology Co., Ltd.
+ */
+
+/dts-v1/;
+
+#include "eic7700.dtsi"
+
+/ {
+	compatible = "sifive,hifive-premier-p550", "eswin,eic7700";
+	model = "SiFive HiFive Premier P550";
+
+	aliases {
+		serial0 = &uart0;
+	};
+
+	chosen {
+		stdout-path = "serial0:115200n8";
+	};
+};
+
+&uart0 {
+	status = "okay";
+};
+
+&uart2 {
+	status = "okay";
+};