ALSA: sc6000: add support for SC-6600 and SC-7000

Add support for later cards based on CompuMedia ASC-9408 chipsets.
These cards were produced by Gallant.

This patch make the OSS aedsp16 driver redundant.

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