AIO cards allow to use AEB (Analogue Expansion Boards) to add four
input and/or output channels.

This patch adds the necessary code to detect and enable the additional
I/O channels.
Signed-off-by: NAdrian Knoth <adi@drcomp.erfurt.thur.de>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>