spi25: Integrate 4BA support

Back port the upstream `commit f43c654a` reworked for our tree.

BUG=chromium:478356
BRANCH=none
TEST=still builds

Change-Id: I95c12d54fcc4acfbce00e59e11d00a324cbfaf7f
Signed-off-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/flashrom/+/1667513
Reviewed-by: Stefan Reinauer <reinauer@google.com>
5 files changed