coreboot/default: add cmocka submodule

otherwise, we get the following from coreboot's build
system, when performin operations in it:

tests/Makefile.mk:31: No system cmocka, build from 3rdparty instead...

However, *we* (Libreboot project) patch coreboot's build system,
so as to not download submodules itself, because lbmk handles
them manually. This is because lbmk's submodule handling has some
extra redundancy features.

Signed-off-by: Leah Rowe <leah@libreboot.org>

config/submodule/coreboot/default/cmocka/module.cfg

@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+subgit="https://review.coreboot.org/cmocka.git"
+subgit_bkup="https://github.com/coreboot/cmocka"
+subhash="8be37372097d1aa5e03b565936db7891b6180e73"

config/submodule/coreboot/default/module.list

@@ -4,6 +4,7 @@
 3rdparty/libgfxinit
 3rdparty/libhwbase
 3rdparty/vboot
+3rdparty/cmocka
 util/crossgcc/tarballs/binutils-2.45.tar.xz
 util/crossgcc/tarballs/gcc-14.2.0.tar.xz
 util/crossgcc/tarballs/gmp-6.3.0.tar.xz