[ALSA] sparc dbri: ring buffered version

It is a complete rework of low level layer to work on ring
buffers for comands and data descriptors. This removes annoying
noise due to delay in data buffer switching.
Signed-off-by: NKrzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NJaroslav Kysela <perex@suse.cz>