Add functions to read Host Firmware Status register and a helper
function to determine if CSE is ready.
BUG=chrome-os-partner:55055
TEST=none
Change-Id: If511a51c04f7e59427d7952fa67b61060e2be404
Signed-off-by: Andrey Petrov <andrey.petrov@intel.com>
Reviewed-on: https://review.coreboot.org/15713
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
