Adapt implementation from skylake. Change-Id: Ica3134a2261d3e84c714264cf75557322f9ef5db Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com> Reviewed-on: https://review.coreboot.org/17673 Tested-by: build bot (Jenkins) Reviewed-by: Patrick Rudolph <siro@das-labor.org> Reviewed-by: Aaron Durbin <adurbin@chromium.org>