x86: Add EFI board code

Add support for the efi-x86 board, which supports running U-Boot as an
EFI 32-bit application.

Signed-off-by: Ben Stoltz <stoltz@google.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/board/efi/Kconfig b/board/efi/Kconfig
new file mode 100644
index 0000000..6f86a48
--- /dev/null
+++ b/board/efi/Kconfig
@@ -0,0 +1,19 @@
+if VENDOR_EFI
+
+choice
+	prompt "Mainboard model"
+	optional
+
+config TARGET_EFI
+	bool "efi"
+	help
+	  This target is used for running U-Boot on top of EFI. In
+	  this case EFI does the early initialisation, and U-Boot
+	  takes over once the RAM, video and CPU are fully running.
+	  U-Boot is loaded as an application from EFI.
+
+endchoice
+
+source "board/efi/efi-x86/Kconfig"
+
+endif