pal: add stereo-channel volume setting

When stream starts with stereo channel, then
if left/right vol is different, the different
gain is set in L/R channel with setting
PARAM_ID_VOL_CTRL_MULTICHANNEL_GAIN. Otherwise
use same gain to set in center channel with
setting PARAM_ID_VOL_CTRL_MASTER_GAIN.

Change-Id: Ifa29a0e45842c186789625730f7bca1b92b7372e
(cherry picked from commit 0501fd79f1acbe49462014eab732a2231e9f5e1e)
3 files changed