ALSA: bebob: add 'version' member for BeBoB protocol version

BeBoB installed devices have BeBoB register area. This area stores
basic information about its firmware. A register has its protocol
version.

This commit adds 'version' member and store the device's protocol
version to handle v3 quirks in following commits.

Tested-by: Kim Tore Jensen <kim@incendio.no>
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Takashi Iwai <tiwai@suse.de>