x86: coreboot: Enable io command

Enable the io command for x86 on coreboot.

Signed-off-by: Simon Glass <sjg@chromium.org>
x86: Add coreboot version to u-boot's version command

Since U-Boot runs from coreboot on x86, the Coreboot version is an
important part of the boot state. This version information is
available in the coreboot tables, so print it when the 'version'
command is used.

Signed-off-by: Simon Glass <sjg@chromium.org>