ALSA: usb-audio: Add mixer mapping for Gigabyte B450/550 Mobos

This patch implements a static mapping for Gigabyte B450/550 Mobos so
that the mixer elements appear reasonably and jack detections work
properly.

Reported-and-tested-by: Brock Szuszczewicz <brock@system76.com>
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=215988
Link: https://lore.kernel.org/r/20220525122018.3299-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>