mb/google/*: Use newly added Chrome EC boardid function

Instead of duplicating code across multiple mainboards, use newly
added helper function to read boardid from Chrome EC.

Change-Id: I1671c0a0b87d0c4c45da5340e8f17a4a798317ca
Signed-off-by: Furquan Shaikh <furquan@chromium.org>
Reviewed-on: https://review.coreboot.org/21682
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Sumeet R Pawnikar <sumeet.r.pawnikar@intel.com>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
36 files changed