vboot: Use VBNV_BLOCK_SIZE from header

This removes a Kconfig variable in favor of using a #define from
vboot_api.h.

BUG=none
BRANCH=none
TEST=built and booted on veyron_mickey

Change-Id: I51312ed0b8d6e2fc94ac8a751e2c06645b87d49b
Signed-off-by: David Hendricks <dhendrix@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/278276
Reviewed-by: Julius Werner <jwerner@chromium.org>
3 files changed