modules: firmware groups attempt two

[Dave Airlie]

This is a second attempt at firmware grouping so we can have dracut
only pull one firmware into the initramfs instead of a bunch of legacy ones.

v1 got derailed when it was pointed out that ordering isn't consistent in
modinfo with C to sections, so that plan no longer was feasible.

This was the simplest next best option, it keeps the group tags, and
adds a new list of acceptable firmwares. New dracut will ignore legacy
firmware in favour of the list, old dracut will just read the legacy info
lines.

This is ugly because it requires duplication, but I can't think of a nice
way beyond horrible unscaleable C preprocessor tricks to make it nicer.

Dave.