ec/google/wilco: Add devicetree chip infrastructure

ec/google/wilco: Add devicetree chip infrastructure

Add a chip_operations structure for Wilco EC and hook it into the device
tree so it can be initialized at boot.

Reserve the device resources specified in Kconfig, which will also
create the device IO windows if they have not been created in bootblock.
If the IO windows already exist (becauase they were specified in the
mainboard devicetree.cb) then this will find the existing entry instead.

During device init stage prepare the keyboard for use, which is required
for it to be functional in firmware and OS with this EC.  Also send a
command to the EC telling it to pass the power button through to the
host for processing.

Change-Id: I0adb01cf394f939f4a28aeb47fe4d0bcda5957d9
Signed-off-by: Duncan Laurie <dlaurie@google.com>
Reviewed-on: https://review.coreboot.org/29117
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>