vboot/ui: Split out enabling/disabling buttons from log_page_* functions

Add a new log_page_update function to maintain the state of page up/down
buttons.

BUG=b:174127808
TEST=make clean && CC=x86_64-pc-linux-gnu-clang make runtests
BRANCH=none

Signed-off-by: Chung-Sheng Wu <chungsheng@google.com>
Change-Id: I6c396af3139229771557f017b816ea93aba27be2
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/vboot_reference/+/2641979
Tested-by: Chung-Sheng Wu <chungsheng@chromium.org>
Commit-Queue: Chung-Sheng Wu <chungsheng@chromium.org>
Reviewed-by: Meng-Huan Yu <menghuan@chromium.org>
1 file changed