ALSA: hda - Halve too large volume scales for STAC/IDT codecs

STAC/IDT codecs have often too large volume scales such as -96dB,
and exposing this as is results in too large scale in percentage
representation.

This patch adds the check of the volume scale and halves the
volume range if it's too large automatically.

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