sound: do something useful with jack interrupts.

[libv]

[ 213.004477] sun4i-codec 1c22c00.codec: Microphone Jack: connected.
[ 215.104467] sun4i-codec 1c22c00.codec: Microphone Jack: disconnected.
[ 224.124227] sun4i-codec 1c22c00.codec: Headphone Jack: connected.
[ 226.494192] sun4i-codec 1c22c00.codec: Headphone Jack: disconnected.

Nice, but not useful.

So, todo: adjust mixer settings and notify userspace tool when new connections appear.