ALSA: fireface: code refactoring to decide name of sound card

This commit uses enumeration constants as index of table for the
list of name of sound card.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20200510074301.116224-5-o-takashi@sakamocchi.jp


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