vboot: Fix EC_SLOW_UPDATE kconfig option

If this is set as bool without help text then it can not be overridden
in defconfig and this option is forever disabled, meaning no boards will
display an update screen when they should.

TEST=ec software sync on sarien with critical update screen visible

Change-Id: I8821cf4c6d5737be82b2881afc1b6bc70392fbb7
Signed-off-by: Duncan Laurie <dlaurie@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/depthcharge/+/1581910
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@chromium.org>
1 file changed