x86: coreboot: Decode additional coreboot sysinfo tags

Add support for decoding tags for GPIOs, compile/build info, cbmem and
other features.

Signed-off-by: Stefan Reinauer <reinauer@chromium.org>
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Signed-off-by: Gabe Black <gabeblack@chromium.org>

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