git.sh: fix invalid command in git_prep()

"./update project trees" is a leftover from the
old build system design, prior to audits.

this particular call is for when xtree is defined,
which means that a given tree must rely on the given
coreboot tree defined by xtree. the "xtree" tree is
downloaded, so that its crossgcc builds can be re-used
to save time when building targets across many trees.

this is because trees often use identical crossgcc builds.

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

0 files changed, 0 insertions, 0 deletions