ASoC: Add json-schema documentation for sound-name-prefix

The 'sound-name-prefix' is used to prepend suitable strings to a
component widgets or controls. This is helpful when there are
multiple instances of the same component. Add relevant json-schema
and is inspired from sound-name-prefix.txt documentation.

Signed-off-by: Sameer Pujar <spujar@nvidia.com>
Cc: Jerome Brunet <jbrunet@baylibre.com>
Cc: Rob Herring <robh+dt@kernel.org>
Reviewed-by: Jerome Brunet <jbrunet@baylibre.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/1630686919-19495-2-git-send-email-spujar@nvidia.com


Signed-off-by: Mark Brown <broonie@kernel.org>