spd: Add a placeholder SPD file to spd/

When a new variant is created, its SPD_SOURCES contains a placeholder
file, to avoid a build failure due to SPD_SOURCES being empty. Currently
these placeholder files live with the rest of the SPD files in soc and
mainboard directories, e.g.
src/soc/intel/alderlake/spd/placeholder.spd.hex

Add a similar placeholder SPD file to the new spd/ directory.

BUG=b:191776301
TEST=None

Signed-off-by: Reka Norman <rekanorman@google.com>
Change-Id: Ia6d76ed512a7e44221fc93ad960790be575c44c2
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57732
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

0 files changed, 0 insertions, 0 deletions