v3/ec: add missing dts properties that are required by upstream zephyr

The upstream zephyr requires the clock source and divider for the
ST ADC. The values set are the same as before the change that allowed
to specify them.

BUG=b:319924603
TEST=Compile EC with upstream version of zephyr

Change-Id: Ie93fa6548748a02a38ac67a984389d771af157eb
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/chameleon/+/5213305
Reviewed-by: Alexandru Stan <amstan@chromium.org>
Commit-Queue: Michał Barnaś <barnas@google.com>
Tested-by: Michał Barnaś <barnas@google.com>
1 file changed