This change replaces `struct cse_layout_regions` with an array of `struct region` and introduces enums for DP and BP[1-4]. This makes it easier to loop over the different regions in following changes. BUG=b:189177186 Change-Id: If3cced4506d26dc534047cb9c385aaa9418d8522 Signed-off-by: Furquan Shaikh <furquan@google.com> Reviewed-on: https://review.coreboot.org/c/coreboot/+/58214 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>