cheza: Enable low power idle mode
cheza: Enable low power idle mode

Cheza should be able to use the low power idle mode for the npcx EC
to get lower power in S3, and in S5 before we enter hibernate

BUG=b:117222355
BRANCH=none
TEST=build and boot on Cheza, Enter S5. See power consumption go down
by 3mw.

Change-Id: Ica011c10b9771695c85b738f45878ae96bba5c5f
Reviewed-on: https://chromium-review.googlesource.com/1258575
Commit-Ready: Ravi Chandra Sadineni <068c0dca42d898d893968d7098b20075cb89039f@chromium.org>
Tested-by: Ravi Chandra Sadineni <068c0dca42d898d893968d7098b20075cb89039f@chromium.org>
Reviewed-by: Wai-Hong Tam <04b587fdf5845741a0c5a8b9cd59ca72d73ef8fc@google.com>

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