After `make clean` a new build should not be based on stale artifacts. Hence we have to remove them. Change-Id: I18292c674986078d991668124193b6aa31234d47 Signed-off-by: Nico Huber <nico.huber@secunet.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/44179 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Angel Pons <th3fanbus@gmail.com>