utils/checkpackagelib: CommentsMenusPackagesOrder: properly initialize levels
Fix an issue introduced by Arnout while committing. Jerzy originally
initialized the menu_of_packages, package and print_package_warning
members like they should be, but Arnout thought it wasn't needed and
removed that.
It is actually needed, to make sure the top level (level 0) works.
Fixes: https://gitlab.com/buildroot.org/buildroot/-/jobs/264383157
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>