cards: allow sysdefault device string
cards: allow sysdefault device string

The "sysdefault" name became also standard, thus we accept it just
like "hw" and "default".

Signed-off-by: Takashi Iwai <4596b3305151c7ee743192a95d394341e3d3b644@suse.de>

tiwai/salsa-lib,tiwai/salsa-lib