ASoC: audio-graph-card: Refactor schema

ASoC: audio-graph-card: Refactor schema

There can be customized sound cards which are based on generic audio
graph. In such cases most of the stuff is reused from generic audio
graph. To facilitate this, refactor audio graph schema into multiple
files and the base schema can be reused for specific sound cards.

The graph card nodes and port nodes are separate entities, so they
should be separate schemas.

Signed-off-by: Sameer Pujar <spujar@nvidia.com>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
[robh: Split out port schema. Add graph.yaml in subsequent commit]
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Sameer Pujar <spujar@nvidia.com>
Link: https://lore.kernel.org/r/20201117013349.2458416-2-robh@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>