x86: Add support for running Intel reference code

Intel has invented yet another binary blob which firmware is required to
run. This is run after SDRAM is ready. It is linked to load at a particular
address, typically 0, but is a relocatable ELF so can be moved if required.

Add support for this in the build system. The file should be placed in the
board directory, and called refcode.elf.

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 64c824f..1a9fa40 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -327,6 +327,17 @@
 	  memory reference code and must be set correctly or the board will
 	  not boot.
 
+config HAVE_REFCODE
+        bool "Add a Reference Code binary"
+        help
+          Select this option to add a Reference Code binary to the resulting
+          U-Boot image. This is an Intel binary blob that handles system
+          initialisation, in this case the PCH and System Agent.
+
+          Note: Without this binary (on platforms that need it such as
+          broadwell) U-Boot will be missing some critical setup steps.
+          Various peripherals may fail to work.
+
 config SMP
 	bool "Enable Symmetric Multiprocessing"
 	default n