uboot-imx

x86: efi: payload: Make EFI payload build again

Since commit 73c5c39 "Makefile: Drop unnecessary -dtb suffixes",
EFI payload does not build anymore. This fixes the build.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>