ALSA: hda - Fix proc output for ADC amp values of CX20549

The CX20549 has only one single input amp on it's input converter
widget. Fix printing of values in the codec file in /proc/asound.

Signed-off-by: Michael Karcher <kernel@mkarcher.dialup.fu-berlin.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>