x86: slimbootloader: Add a slimbootloader device tree

Add a new device tree which has very minimum nodes
- x86 reset
- x86 tsc_timer
- x86 pci
- Slim Bootloader serial

Signed-off-by: Aiden Park <aiden.park@intel.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>

arch/x86/dts/Makefile

@@ -18,6 +18,7 @@ dtb-y += bayleybay.dtb \
 	qemu-x86_i440fx.dtb \
 	qemu-x86_q35.dtb \
 	theadorable-x86-dfi-bt700.dtb \
+	slimbootloader.dtb \
 	baytrail_som-db5800-som-6867.dtb
 
 targets += $(dtb-y)

arch/x86/dts/slimbootloader.dts

@@ -0,0 +1,27 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019 Intel Corporation <www.intel.com>
+ */
+
+/dts-v1/;
+
+/include/ "skeleton.dtsi"
+/include/ "reset.dtsi"
+/include/ "tsc_timer.dtsi"
+
+/ {
+	model = "slimbootloader x86 payload";
+	compatible = "slimbootloader,x86-payload";
+
+	chosen {
+		stdout-path = &serial;
+	};
+
+	serial: serial {
+		compatible = "intel,slimbootloader-uart";
+	};
+
+	pci {
+		compatible = "pci-x86";
+	};
+};