S25FL256x: Initial write-protect support

This adds processing logic and ranges for write-protection for
Spansion S25FL256x chips.

BUG=chrome-os-partner:36894
BRANCH=none
TEST=successfully ran flashrom --wp-range, --wp-enable, and
--wp-disable commands on Whirlwind (using Servo).

Signed-off-by: David Hendricks <dhendrix@chromium.org>
Change-Id: I621babddffe5dba4c956d379fe887a94969b7c30
Reviewed-on: https://chromium-review.googlesource.com/253831
Reviewed-by: Shawn N <shawnn@chromium.org>
2 files changed