google/enguarde: Upstream Lenovo N21 Chromebook

Migrate google/enguarde (Lenovo N21 Chromebook) from Chromium tree to
upstream, using google/rambi as a reference.

original source:
branch firmware-enguarde-5216.201.B
commit cf1f57b [Enguarde: Adjust rx delay for norm.]

TEST=built and booted Linux on enguarde with full functionality

blobs required for working image:
VGA BIOS (vgabios.bin)
firmware descriptor (ifd.bin)
Intel ME firmware (me.bin)
MRC (mrc.elf)
external reference code (refcode.elf)

Change-Id: I3ccda29d1e095d8b1b36766cda913172f72233a7
Signed-off-by: Matt DeVillier <matt.devillier@gmail.com>
Reviewed-on: https://review.coreboot.org/15444
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
34 files changed