Add factory and recovery image layouts for basic nand based targets

The exact image layout might require fine tuning, but we need to add
something to prevent canary builder failures.

BUG=chrome-os-partner:36851
TEST=the following cgtp.py invocation now succeeds:
 $ ~/trunk/src/scripts/build_library/cgpt.py validate factory_install \
  /mnt/host/source/src/private-overlays/overlay-urara-private/scripts/disk_layout.json

Change-Id: I87ba723bd0e815da72659bd215c37d4d19588f6a
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/250832
Reviewed-by: Daniel Ehrenberg <dehrenberg@chromium.org>
1 file changed