zephyr: krabby: dts: Set the property of prescale-scl-low
zephyr: krabby: dts: Set the property of prescale-scl-low

The property of prescale-scl-low can adjust the low period of
the SCL clock.

BUG=b:218425573
BRANCH=none
TEST=zmake build krabby --clobber
When set the prescale-scl-low to >=1 can make I2C3 and I2C4
SI tLOW test pass.

Signed-off-by: Tim Lin <38846f7070d5770410e9ef8b439c72e7b53a72c5@ite.corp-partner.google.com>
Change-Id: Icd6a5b0a63f78b4681792e45ee4d1ea8f9e9ffcd
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3551741
Reviewed-by: Ting Shen <c671d3efec3d7e7e285f3788bf0d1ba4c8605b78@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec