arm: qemu-ppce500: Add a devicetree file

This uses QEMU virt which creates its own devicetree.

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

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

arch/powerpc/dts/Makefile

@@ -18,6 +18,7 @@ dtb-$(CONFIG_TARGET_P2041RDB) += p2041rdb.dtb
 dtb-$(CONFIG_TARGET_P3041DS) += p3041ds.dtb
 dtb-$(CONFIG_TARGET_P4080DS) += p4080ds.dtb
 dtb-$(CONFIG_TARGET_P5040DS) += p5040ds.dtb
+dtb-$(CONFIG_TARGET_QEMU_PPCE500) += qemu-ppce500.dtb
 dtb-$(CONFIG_TARGET_SOCRATES) += socrates.dtb
 dtb-$(CONFIG_TARGET_T1024RDB) += t1024rdb.dtb
 dtb-$(CONFIG_TARGET_T1042D4RDB) += t1042d4rdb.dtb

arch/powerpc/dts/qemu-ppce500.dts

+// SPDX-License-Identifier: GPL-2.0+ OR MIT
+/*
+ * Empty device tree for qemu-ppce400
+ *
+ * Copyright 2021 Google LLC
+ */
+/dts-v1/;
+
+/ {
+};

configs/qemu-ppce500_defconfig

 CONFIG_PPC=y
 CONFIG_SYS_TEXT_BASE=0xf01000
 CONFIG_ENV_SIZE=0x2000
+CONFIG_DEFAULT_DEVICE_TREE="qemu-ppce500"
 CONFIG_MPC85xx=y
 # CONFIG_CMD_ERRATA is not set
 CONFIG_TARGET_QEMU_PPCE500=y