arm: xenguest_arm64: Add a empty devicetree file

Add an empty version of this file, so that we can at least build this
board when devicetrees are required.

The real devicetree is created by the Xen project on-the-fly.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/arm/dts/Makefile

@@ -1140,6 +1140,8 @@ dtb-$(CONFIG_ARCH_MEDIATEK) += \
 	mt8516-pumpkin.dtb \
 	mt8518-ap1-emmc.dtb
 
+dtb-$(CONFIG_XEN) += xenguest-arm64.dtb
+
 dtb-$(CONFIG_TARGET_GE_BX50V3) += \
 	imx6q-bx50v3.dtb \
 	imx6q-b850v3.dtb \

arch/arm/dts/xenguest-arm64.dts

+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Empty devicetree file for xenguest_arm64
+ *
+ * This is required to make the board build with CONFIG OF_SEPARATE
+ * Build instructions at xenguest_arm64.rst are inadequate for obtaining a real
+ * devicetree.
+ *
+ * Copyright 2021 Google LLC
+ */
+
+/dts-v1/;
+
+/ {
+};

configs/xenguest_arm64_defconfig

@@ -3,7 +3,7 @@ CONFIG_POSITION_INDEPENDENT=y
 CONFIG_TARGET_XENGUEST_ARM64=y
 CONFIG_SYS_TEXT_BASE=0x40080000
 CONFIG_SYS_MALLOC_LEN=0x2000000
-CONFIG_SYS_MALLOC_F_LEN=0x2000
+CONFIG_DEFAULT_DEVICE_TREE="xenguest-arm64"
 CONFIG_IDENT_STRING=" xenguest"
 CONFIG_SYS_LOAD_ADDR=0x40000000
 CONFIG_BOOTDELAY=10