Modules: CS4231 driver

Clean up ISA cs4231 code, removing experimental EBUS/SBUS merge,
to improve readability.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!