[ALSA] dbri driver cleanup

This is a small clean up of the dbri driver for sparc machines.
It contains also a fix to DBRI interrupt queue initialization.

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>