templates: add ddr4-spd-empty.hex to SPD_SOURCES

We need at least one SPD in SPD_SOURCES when creating a new variant
of trembyle or dalboz, or else coreboot won't build. Add the empty
DDR4 SPD so that we can build the new variant.
Add an empty mem_parts_used.txt so that the developer can add the
supported memory parts and regenerate spd/Makefile.inc using
spd_tools.

BUG=b:169199396
TEST=create a new variant of dalboz or trembyle and observe that
the build succeeds.

Signed-off-by: Paul Fagerburg <pfagerburg@chromium.org>
Change-Id: I764690c76529780186d0a1d156a623821f9d6972
Reviewed-on: https://review.coreboot.org/c/coreboot/+/45638
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Rob Barnes <robbarnes@google.com>

0 files changed, 0 insertions, 0 deletions