ASoC: define playback and capture streams in dummy codec

This patch adds a playback and capture streams to the dummy codec DAI
configuration. Most permissive set of sampling rates and formats is used.

This patch is needed for playback and capturing on a codec-less systems,
as otherwise the PCM device nodes are not even created.

Signed-off-by: Stas Sergeev <stsp@users.sourceforge.net>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>