[ALSA] hda-codec - Fix AD1988 capture elements

The some indices of capture elements of AD1988 are wrongly assigned.
This patch fixes it.  See ALSA bug#3795
	https://bugtrack.alsa-project.org/alsa-bug/view.php?id=3795

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