ALSA: ctxfi - Allow unknown PCI SSIDs

Allow unknown PCI SSIDs for emu20k1 and emu20k2 as "unknown" model.
Also, add a black-list check in case any device has to be listed
as "unsupported".  It has a negative value in the pci quirk entry.

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