Add a function which handles translation of PWROK from logical level
to physical level.
Also implement chipset_force_shutdown() in gaia_power.c, so PMU code
doesn't need to know about PWROK physical level.
BUG=chrome-os-partner:18738
BRANCH=none
TEST=build all platforms; boot spring
Change-Id: I360266ef89b6ead49a633cd57b7530f791b04c9e
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/48251
Reviewed-by: Bill Richardson <wfrichar@chromium.org>