ICL: Modify force_shutdown to meet PCH timing requirements
ICL: Modify force_shutdown to meet PCH timing requirements

Time between RSMRST going low and the _A rails dropping 5% must be >
400 ns. To meet this timing set the PCH pass through low at beginning
of chipset_force_shutdown. Similarly, set EC_PCH_DSW_PWROK low to meet
its timing requirement relative to _A rails dropping 5%.

BUG=b:112170058
BRANCH=none
TEST=Verified that timing meets the specifications.

Change-Id: I88573a4b926f5804d1a0df5702078eb32a6d0221
Signed-off-by: Scott Collyer <7d40b3eb9e17bf55d972074a5e77a7ea4159f9dd@google.com>
Reviewed-on: https://chromium-review.googlesource.com/1179142
Commit-Ready: Scott Collyer <7d40b3eb9e17bf55d972074a5e77a7ea4159f9dd@chromium.org>
Tested-by: Scott Collyer <7d40b3eb9e17bf55d972074a5e77a7ea4159f9dd@chromium.org>
Reviewed-by: Furquan Shaikh <6be5c96c464778f89679b1062a2e0a6af93d2aa5@chromium.org>

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