git.sh: *never* run git submodule update

only use config/submodules/ which the build system then
uses to run git clones manually, replicating the submodules
feature. we must never use a project's own gitmodules feature,
because we can't easily control it. better to let it break first,
and then figure out what modules to add manually, so that we
have only what we need for each project.

it's done this way, because git's own submodules feature
doesn't have very good error checking in general, nor
does it have good redundancy.

with the current design, we can declare backup repositories
for each submodule.

we replicate it precisely. for example:

3rdparty/vboot

this is a coreboot submodule, and we handle that in the
coreboot trees.

however, our current design also allows you to do this even
if the upstream repository does not contain a .gitmodules file

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

include/git.sh

@@ -109,9 +109,6 @@ prep_submodules()
 	if [ -f "$mdir/module.list" ]; then
 		cat "$mdir/module.list" > "$tmpdir/modules" || \
 		    $err "!cp $mdir/module.list $tmpdir/modules"
-	elif [ -f "$tmpgit/.gitmodules" ]; then
-		git -C "$tmpgit" submodule status | awk '{print $2}' > \
-		    "$tmpdir/modules" || $err "$mdir: cannot list submodules"
 	else
 		return 0
 	fi
@@ -141,9 +138,6 @@ fetch_submodule()
 			[ -d "$tmpgit/$1" ] && break
 		done
 		[ -d "$tmpgit/$1" ] || $err "!clone $mod $project $mcfgdir $1"
-	else
-		git -C "$tmpgit" submodule update --init --checkout -- "$1" \
-		    || $err "$mdir: !update $1"
 	fi
 }