Early UART driver is for bootblock and romstage. It is supposed to be used when BOOTBLOCK_CONSOLE is enabled. This also adds few configuration bits in bootblock requiered for serial to be set up. Change-Id: I15520d566f107797e68d618885d4379e73d0fa45 Signed-off-by: Andrey Petrov <andrey.petrov@intel.com> Reviewed-on: https://review.coreboot.org/13677 Tested-by: build bot (Jenkins) Reviewed-by: Aaron Durbin <adurbin@chromium.org>