x86: Use binman all x86 boards

Change x86 boards to use binman to produce the ROM. This involves adding the
image definition to the device tree and using it in the Makefile. The
existing ifdtool features are no-longer needed.

Note that the u-boot.dtsi file is common and is used for all x86 boards which
use microcode. A separate emulation-u-boot-dtsi is used for the others.

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