x86: Support QEMU x86 targets

This commit introduces the initial U-Boot support for QEMU x86 targets.
U-Boot can boot from coreboot as a payload, or directly without coreboot.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>
Merged in patch 'x86: qemu: Add CMD_NET to qemu-x86_defconfig
   https://patchwork.ozlabs.org/patch/479745/
diff --git a/board/emulation/qemu-x86/Kconfig b/board/emulation/qemu-x86/Kconfig
new file mode 100644
index 0000000..e777ef4
--- /dev/null
+++ b/board/emulation/qemu-x86/Kconfig
@@ -0,0 +1,24 @@
+if TARGET_QEMU_X86
+
+config SYS_BOARD
+	default "qemu-x86"
+
+config SYS_VENDOR
+	default "emulation"
+
+config SYS_SOC
+	default "qemu"
+
+config SYS_CONFIG_NAME
+	default "qemu-x86"
+
+config SYS_TEXT_BASE
+	default 0xfff00000
+
+config BOARD_SPECIFIC_OPTIONS # dummy
+	def_bool y
+	select X86_RESET_VECTOR
+	select QEMU
+	select BOARD_ROMSIZE_KB_1024
+
+endif