[PATCH] ascenario: Add scenario support to alsa-lib

[PATCH] ascenario: Add scenario support to alsa-lib

It allows switching audio settings between scenarios or uses-cases like
listening to music and answering an incoming phone call. Made of control
aliasing for playback, capture master and switch as well as the option to
post- and prefix a sequence of control changes avoiding pops and other
unwanted noise. Some example programs will be available in alsa-utils.

CC: Ian Molton <ian@mnementh.co.uk>
CC: Graeme Gregory <gg@slimlogic.co.uk>
Signed-off-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Stefan Schmidt <stefan@slimlogic.co.uk>