sound: Change snd_playback_start/snd_record_start
sound: Change snd_playback_start/snd_record_start

The content of these functions almost exclusively deals with channel
client functionality except one line where the channel's active state is
set to TRUE.

These functions are called in two different places.

The first place is from the public API spice_server_record_start() and
spice_server_playback_start(). These functions should alter the
channel's active state, and then set the associated channel client to
active.

The second place is when a new channel client is created. In this
case, it is only called if the channel is already active, so it doesn't
make much sense to set the channel's active state inside of the
function.

To simplify things (and enable some future refactoring), this function
now only deals with the SndChannelClient. The functions have also been
renamed to reflect this fact. The SndChannel's active state is now only
modified from the public API functions.

Signed-off-by: Jonathon Jongsma <c7254805a17bd5c41e24c3a278fcbf3afcdfb0fa@redhat.com>
Acked-by: Pavel Grunt <fbda40b445316123f12a5a6bd7556918ea74f4bc@redhat.com>

fgouget/spice,fgouget/spice,fgouget/spice,fgouget/spice