AudioFlinger: Better handling for master volume/mute

(cherry picked from commit 93d90683)

> AudioFlinger: Better handling for master volume/mute
>
> Changes to address bug 6842827.
>
> When a HAL is loaded, cache whether or not the HAL supports
> set_master_volume/mute in the AudioHwDevice structure.  Store an
> AudioHwDevice in AudioStream(In|Out) structures instead of just an
> audio_he_device_t.  This give threads (PlaybackThreads in
> particular) access to the cached capabilities.
>
> When setting master volume/mute, change the system to always set the
> setting on all HAL which support it and also to set the setting on all
> PlaybackThreads.  Change PlaybackThreads to apply the setting at the
> in SW mix stage of the pipeline if its assigned HAL does not support
> the setting, or to ignore the setting of the assigned HAL does support
> it.
>
> Change-Id: Ia14137a30b4c3ee6f2d7ddcc8cba87bf5eec87f4
> Signed-off-by: John Grossman <johngro@google.com>

Change-Id: Icb6bc13764e100a2003eb1dee2231132ab287d98
Signed-off-by: John Grossman <johngro@google.com>