ASoC: sti: Update DT example to match the driver code

uniperiph-id, version and mode are ST specific bindings and
need the 'st,' prefix. Update the examples, as otherwise copying
them yields a runtime error parsing the DT node.

Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>