x86: Add support for U-Boot as an EFI application

Add the required x86 glue code. This includes the initial start-up,
relocation and jumping to efi_main(). We also need to avoid fiddling with
interrupts.

Signed-off-by: Ben Stoltz <stoltz@google.com>
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index e8968a7..7e6e89c 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -11,6 +11,9 @@
 config VENDOR_COREBOOT
 	bool "coreboot"
 
+config VENDOR_EFI
+	bool "efi"
+
 config VENDOR_EMULATION
 	bool "emulation"