ALSA: hda - Fix auto-init of output volumes of Realtek codecs

Fix the regression introduced by the commit
1f0f4b80
  ALSA: hda - Reduce static init verbs for Realtek auto-parsers

The input amps of mixer widgets should be unmuted as default (as
usually they have no assigned mixer switches).

More fixes in this commit are, however, for ALC260: ALC260 codec can
have multiple output mixers connnected to a single DAC althouh the
driver didn't pick up them properly.

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