ec/google/chromeec: Add support for EC device events

Add support for the new EC device event interface which is used to
report events from devices that are connected behind the EC.

This can be used to differentiate wake sources from the EC in the case
that the EC has the wake pins from various devices.

This can be used in case the AP is unable to directly wake from the
device itself, for example when using the Deep S3 state on Intel
platforms only a few pins can directly wake the AP.

BUG=b:30624430
TEST=build google/* boards that use chrome EC.  Feature is used and
tested further in a subsequent commit.

Change-Id: I5126c6d6ffb6b0ef6e8db8dcd5aec62db925a371
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://review.coreboot.org/20426
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
4 files changed