x86: Add generic EFI payload support

It is possible to create a generic EFI payload for all x86 boards.
The payload is configured to include as many generic drivers as
possible. All stuff that touches low-level initialization are not
allowed as such is the EFI BIOS's responsibility. Platform specific
drivers (like gpio, spi, etc) are not included.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/x86/dts/Makefile b/arch/x86/dts/Makefile
index 7379774..9872c04 100644
--- a/arch/x86/dts/Makefile
+++ b/arch/x86/dts/Makefile
@@ -11,6 +11,7 @@
 	dfi-bt700-q7x-151.dtb \
 	edison.dtb \
 	efi.dtb \
+	efi-x86_payload.dtb \
 	galileo.dtb \
 	minnowmax.dtb \
 	qemu-x86_i440fx.dtb \