ALSA: hda - Change all ADCs for dual-adc switching mode for Realtek

When the dual-adc switching mode is active in Realtek auto-parser,
we need to couple all ADCs as a single capture-volume.  Currently, the
volume control changes only the first ADC, thus others may remain silent.
This patch fixes the problem.

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