mb/google/poppy: Allow use of optional secondary SPD

This change adds support for variants to use secondary SPD if
required. This enables a variant to have different types of memory
supported using the same image.

BUG=b:73514687

Change-Id: I3add65ead99c510f2d6ec899fbf2cb9a06c79b0c
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/24972
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
3 files changed