arm: mediatek: add support for MediaTek MT7986 SoC

This patch adds basic support for MediaTek MT7986 SoC.
This include the file that will initialize the SoC after boot and its
device tree.

Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Daniel Golle <daniel@makrotopia.org>
diff --git a/arch/arm/dts/mt7986-u-boot.dtsi b/arch/arm/dts/mt7986-u-boot.dtsi
new file mode 100644
index 0000000..95671f8
--- /dev/null
+++ b/arch/arm/dts/mt7986-u-boot.dtsi
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2022 MediaTek Inc.
+ * Author: Sam Shih <sam.shih@mediatek.com>
+ */
+
+&topckgen {
+	u-boot,dm-pre-reloc;
+};
+
+&pericfg {
+	u-boot,dm-pre-reloc;
+};
+
+&apmixedsys {
+	u-boot,dm-pre-reloc;
+};
+
+&timer0 {
+	u-boot,dm-pre-reloc;
+};
+
+&uart0 {
+	u-boot,dm-pre-reloc;
+};
+
+&snand {
+	u-boot,dm-pre-reloc;
+};
+
+&pinctrl {
+	u-boot,dm-pre-reloc;
+};