alsa.conf: change the location for add-on configs to /etc/alsa/conf.d
alsa.conf: change the location for add-on configs to /etc/alsa/conf.d

The add-on configuration files should be placed to a volatile place.

Signed-off-by: Jaroslav Kysela <72edd5e1a572f82f059ccbb83c92b74d6cb051ff@perex.cz>

alsa-project/alsa-lib,tiwai/alsa-lib,alsa-project/alsa-lib,takaswie/alsa-lib,takaswie/alsa-lib,tiwai/alsa-lib,tiwai/alsa-lib,tiwai/alsa-lib,alsa-project/alsa-lib,takaswie/alsa-lib,alsa-project/alsa-lib,takaswie/alsa-lib,takaswie/alsa-lib