mb/lenovo/x1_carbon_gen1: add missing '+' in spd/Makefile

Each line of spd config overwriting the slot 0 instead
of appending it.

Change-Id: I0124aa34f1d4fcb30810fb7eef03d4828a7ac430
Signed-off-by: Alexander Couzens <lynxis@fe80.eu>
Tested-on: lenovo x1 carbon gen 1 with elpida 8GB
Fixes: e9787ff61f81 ("mb/lenovo/x1_carbon_gen1: Add 4GiB SPD index 2")
Reviewed-on: https://review.coreboot.org/20918
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>

0 files changed, 0 insertions, 0 deletions