coreboot/next: merge with coreboot/default

I also cherry-picked a patch from Heads, that fixes build
issues caused by the hacks in the T480 port; several changes
made by Mate are now ifdef'd based on whether a KabyLake
ThinkPad is specified in defconfig.

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

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

@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+subrepo="https://review.coreboot.org/fsp.git"
+subrepo_bkup="https://github.com/coreboot/fsp"
+subhash="86c9111639d357e0f369c14248097b119112a71c"