arch/x86: always use _start as entry symbol for all stages

Instead of keeping track of all the combinations of entry points
depending on the stage and other options just use _start. That way,
there's no need to update the arch/header.ld for complicated cases
as _start is always the entry point for a stage.

Change-Id: I7795a5ee1caba92ab533bdb8c3ad80294901a48b
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/13882
Tested-by: build bot (Jenkins)
Reviewed-by: Andrey Petrov <andrey.petrov@intel.com>
2 files changed