alsa: conf - use card number roots for device redirects

alsa: conf - use card number roots for device redirects

The change device definitions (pcm.front etc.) from the driver
roots (cards.<DRIVER_NAME>) to the card number roots (cards.<CARDNO>).

This will allow us to do custom overrides (like UCM) in
/var/lib/alsa/card<CARDNO>.conf.d.

For dmix and dsnoop default values, use the card ID instead
the card driver name. It's more flexible.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>