lo-pack-sources: use module instead of piece

we use git submodules, so it makes more sense (hopefully)

Replaced options:
    --no-lo-pieces with --no-submodule
    --piece=<piece> with --module=<module>

Removed hopefully unused option:
    --no-lo-core

Change-Id: Icbf742991ccda2f7833a5b50d51cb1421885383d