project.py: pass --recurse-submodules={value}

If submodules is False, explicitly pass '=no'.  Uninitialized submodules
may cause the default option to fail.

Change-Id: Ia00bcba5b69c4b65195f4c469c686a3ef9a4a3ad
Reviewed-on: https://gerrit-review.googlesource.com/c/git-repo/+/330159
Reviewed-by: Xin Li <delphij@google.com>
Tested-by: LaMont Jones <lamontjones@google.com>